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If you US guys are still trying to sort out your saggy rear ends, Then a little bit of research goes a long way.

The ONLY currently available off-the-shelf option for springs is H&R.
Front lowered by 50mm. Rear Raised by 15mm

Currently, the only off-the-shelf Performance Dampers are Koni Red Adjustable. It is possibly because these are already available for other vehicles in the same physical configuration, unlike Bilstein /Sachs, the bracket kit for the lower eye is separate. If you want Bilsteins, you will be looking at custom valved options for 6100 style units and those are quite pricey.

If you want anything else or something even more specific, then you'll have to get off your arses and take the vehicle to a dedicated race suspension workshop (Ground Control springs to mind, no pun intended) and leave your vehicle there for corner weighting, as well as spring & damper configuration for your desired 'performance' outcome.
Ground Control already have experience with W201track oriented performance setups, which obviously can be adapted to W124 with some spring rate changes and adjustment to front damper rates. But for a 107... well... nothing.

Availability is simply not the case with the R107 - because honestly noone is interested in being the guineapig. Those who have seriously modified their vehicles to "competition" level have severely compromised the vehicles 'daily use' abilities.

But let me make this abundantly clear at the outset.

You CANNOT make an R107 handle like a racecar. The SLC has the 'better' chance with the fixed roof, but the roadster has WAY too much chassis twist and scuttle shake. Combine that with suspension that is isolated from the chassis via elastomeric bushes in subframe cradles, and you have a LOT more work to do to 'sharpen' the handling. Those of us who have gone the polyurethane route can tell you that the NVH levels and rattle noises go through the roof (whether it's on or not, again no pun intended) and the harshness is not easily dialled out.

It also increases torsional stresses to the point where subframes develop cracking.

The absolute best thing you can do is either keep the vehicle 100% factory standard, or live with the fact that any modifications will inevitably reduce overall driveability and comfort - and increase the vehicle maintenance requirements.

I've done more than my fair share of non-stop interstate trips in all my MB's and the R107 was originally very comfortable, quiet and effortless. Stuff-all room for luggage though, and in standard trim, reasonably powerful for overtakes and highway manners.

But I couldn't leave it alone, could I...

Hand on heart, there is now no way in hell I would take the 107 on another 5600km round trip again. I'll leave that to the e63. Not because of age or power or comfort. but because of the relative effortless driving difference.
Both cars are 'enthusiast' cars, and the R107 has roof-off cache. It's also got a Messerschmitt-level exhaust and will chew twice as much fuel per 100km than the 5.5 biturbo amg when flogging it. It sits low, and looks the business driving through town. On the highway it's a noisy pig.
Urethane bushes remove the front end vagueness but introduce some kickback in the steering and in the front subframe, making 'little' bumps much harsher, ironing out the super-evil pothole bumps to a "did I just break my 3pc OZ rims?" feeling. Our highways are by other continenental standards... well - let's just say our highways are like your unpaved backroads and leave it at that.

There is absolutely nothing wrong with H&R's sport springs, but they are not for iron block 107's. at least not in the front. 50mm lower IS 50mm. In fact it would be mandatory to use new shims of at least 18mm in the front if you want to keep a little more travel... and save the bumpstops a bit... and that's on the alloy block.

The Koni's are exceptional. Given I run B8 Bilsteins in all the 124's and H&R springs and urethane bushes and custom 5 link rears I can say that the 107's difference in suspension design DOES account for more than 50% of the handling anomalies with regards to harshness vagueness and the scuttle-shake / rattles that come with attempting to "improve" the vehicle.

So, does the off-the-shelf solution present any negatives? Yep. Front's pretty darn low, but if you're careful you can live with it. Or shim the springs up with the 18mm or maybe add another ring

If you want to know about the urethane subframe mounts, I do not make them any more. Yes they will outlast anything currently available. Yes they DO improve the front end feeling, but they need LCA bushes as well to work properly.
The LCA bushes are a problem, because the design of the lower arm does not allow for a sufficient thickness of the bush to compensate for any seriously jarring impacts. Using a harder material makes the problem worse, and as experienced owners know, the LCA mounts on the subframes, even on the revised subframe version, is a very flimsy design.

So what to do? simple. Use genuine MB LCA bushes and good TRW or Lemforder balljoints, and Genuine MB subframe bushes. At least they last... provided you don't spray them down with leaky ATF or Oil from your engine.

After having tried several different urethane hardnesses, Anything more than 10º above factory becomes too harsh. YES, it does stiffen the steering relationship up a bit. Yes you need to make sure your draglink and tierods and idler arm bushes are in tiptop shape... Yes your steering damper will work a lot harder...

Originally I machined some 95º urethane for the LCA bushes, preferring to use a thin alloy ferrule for the bolt, and omitted the compression discs.
Later it proved to be a source of tearing on the outer face, due mostly to the subframe, and this is not easily rectified (and why 107's use steel chafered bushes in the LCA)
using a thicker alloy ferrule and machined washers, having to step them into the bush made for a well-engineered but excessively time consuming practice with no real improvement in NVH. The steering was certainly more direct, but when you can feel every stone on the road, and the wheel reacts to it, you know it's more than a few steps too far.

Finding out the factory hardness is not as simple as it sounds. Firstly, some bushes are stamped. usually 30º,45º and 75º but not always. testing an old bush yields inconsistent results.
Testing a recently installed bush ALSO yields inconsistent results. Testing a New genuine bush - yep... slightly less inconsistent, but the variation is still apparent. Most of this is to do with the steel chafer ring that is inside the LCA bush. That's there to promote stability and reduce tearing and flex. No wonder when the LCA has the tiniest bushes known to man. At least they rectified that with w201 and w124 -> models.

But this is all going the wrong way. Mercedes-Benz designed these vehicles in the 1960's. They were designed with slide rules and primitive computers. Engineering plans were on paper, drafted by real draftsmen, not some CAD dwg or dxf file.
even NC machining was in it's infancy. Noone should expect a comparison to modern vehicle engineering with all it's modelling to be remotely comparable.

There are inherent design flaws in the 107, with the subframes being the most obvious in terms of torsional rigidity and point loading. The lack of stiffness due to having no roof, and a distinct lack of reinforcing to the floorpan in the door void contributes to the flex. This is not something that can be rectified without some serious unpicking of sills and structural bracing in honeycomb, with appropriate lateral reinforcing tied in.

So without going to "extreme levels" of re-fabricating the shell, trying to make the vehicle handle without a significant increase in chassis flex and NVH is an exercise in futility.

Beyond the most basic understanding that the tyre sidewall and damper address most of the harshness, and a stiffening in either of these areas will naturally increase the 'firmness' of the ride and slightly improve handling characteristics, there is always an equal negative. In this case it is scuttle shake, and noise/harshness.

Even the most benign improvements come with a compromise.

Before contemplating any perceived "improvements" try driving a vehicle with completely factory original suspension that has been recently overhauled. You may be surprised at how capable and quiet it is, IF you can live with the body roll characteristics that these vehicles exhibited. (That was how it was done back in the day because tyres were of dubious grip level)

If you want minimal 'improvement' then new steering components and bushes, new LCA's and new subframe bushes will highlight any inadequacies of aged springs or failing dampers, at which point you can choose to replace OE or go for an off-the-shelf solution or go further and corner weigh the vehicle and custom spring/damper rates for your particular application.

Lastly, There were some anti-roll bars which help the front springs, but they are sufficiently stiff enough to transfer the torsion into the chassis where the door voids are. If you want to understand how this is possible, put a jack under one front wheel and leave the other on the ground.... jack it up until you see the rear wheel come off the ground.... the amount of twist in the chassis will most likely alarm you.
It's worse with the hardtop off, obviously. Oh, and don't do it with the softtop raised, or you'll bend the spars. Trust me.

Here are the H&R spring specs and Koni red adjustable damper specs, and the shim part numbers for the front.
w123(r107)front shims.png
 

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Registered
1983 280SL 5 Speed
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73 Posts
If you US guys are still trying to sort out your saggy rear ends, Then a little bit of research goes a long way.

The ONLY currently available off-the-shelf option for springs is H&R.
Front lowered by 50mm. Rear Raised by 15mm

Currently, the only off-the-shelf Performance Dampers are Koni Red Adjustable. It is possibly because these are already available for other vehicles in the same physical configuration, unlike Bilstein /Sachs, the bracket kit for the lower eye is separate. If you want Bilsteins, you will be looking at custom valved options for 6100 style units and those are quite pricey.

If you want anything else or something even more specific, then you'll have to get off your arses and take the vehicle to a dedicated race suspension workshop (Ground Control springs to mind, no pun intended) and leave your vehicle there for corner weighting, as well as spring & damper configuration for your desired 'performance' outcome.
Ground Control already have experience with W201track oriented performance setups, which obviously can be adapted to W124 with some spring rate changes and adjustment to front damper rates. But for a 107... well... nothing.

Availability is simply not the case with the R107 - because honestly noone is interested in being the guineapig. Those who have seriously modified their vehicles to "competition" level have severely compromised the vehicles 'daily use' abilities.

But let me make this abundantly clear at the outset.

You CANNOT make an R107 handle like a racecar. The SLC has the 'better' chance with the fixed roof, but the roadster has WAY too much chassis twist and scuttle shake. Combine that with suspension that is isolated from the chassis via elastomeric bushes in subframe cradles, and you have a LOT more work to do to 'sharpen' the handling. Those of us who have gone the polyurethane route can tell you that the NVH levels and rattle noises go through the roof (whether it's on or not, again no pun intended) and the harshness is not easily dialled out.

It also increases torsional stresses to the point where subframes develop cracking.

The absolute best thing you can do is either keep the vehicle 100% factory standard, or live with the fact that any modifications will inevitably reduce overall driveability and comfort - and increase the vehicle maintenance requirements.

I've done more than my fair share of non-stop interstate trips in all my MB's and the R107 was originally very comfortable, quiet and effortless. Stuff-all room for luggage though, and in standard trim, reasonably powerful for overtakes and highway manners.

But I couldn't leave it alone, could I...

Hand on heart, there is now no way in hell I would take the 107 on another 5600km round trip again. I'll leave that to the e63. Not because of age or power or comfort. but because of the relative effortless driving difference.
Both cars are 'enthusiast' cars, and the R107 has roof-off cache. It's also got a Messerschmitt-level exhaust and will chew twice as much fuel per 100km than the 5.5 biturbo amg when flogging it. It sits low, and looks the business driving through town. On the highway it's a noisy pig.
Urethane bushes remove the front end vagueness but introduce some kickback in the steering and in the front subframe, making 'little' bumps much harsher, ironing out the super-evil pothole bumps to a "did I just break my 3pc OZ rims?" feeling. Our highways are by other continenental standards... well - let's just say our highways are like your unpaved backroads and leave it at that.

There is absolutely nothing wrong with H&R's sport springs, but they are not for iron block 107's. at least not in the front. 50mm lower IS 50mm. In fact it would be mandatory to use new shims of at least 18mm in the front if you want to keep a little more travel... and save the bumpstops a bit... and that's on the alloy block.

The Koni's are exceptional. Given I run B8 Bilsteins in all the 124's and H&R springs and urethane bushes and custom 5 link rears I can say that the 107's difference in suspension design DOES account for more than 50% of the handling anomalies with regards to harshness vagueness and the scuttle-shake / rattles that come with attempting to "improve" the vehicle.

So, does the off-the-shelf solution present any negatives? Yep. Front's pretty darn low, but if you're careful you can live with it. Or shim the springs up with the 18mm or maybe add another ring

If you want to know about the urethane subframe mounts, I do not make them any more. Yes they will outlast anything currently available. Yes they DO improve the front end feeling, but they need LCA bushes as well to work properly.
The LCA bushes are a problem, because the design of the lower arm does not allow for a sufficient thickness of the bush to compensate for any seriously jarring impacts. Using a harder material makes the problem worse, and as experienced owners know, the LCA mounts on the subframes, even on the revised subframe version, is a very flimsy design.

So what to do? simple. Use genuine MB LCA bushes and good TRW or Lemforder balljoints, and Genuine MB subframe bushes. At least they last... provided you don't spray them down with leaky ATF or Oil from your engine.

After having tried several different urethane hardnesses, Anything more than 10º above factory becomes too harsh. YES, it does stiffen the steering relationship up a bit. Yes you need to make sure your draglink and tierods and idler arm bushes are in tiptop shape... Yes your steering damper will work a lot harder...

Originally I machined some 95º urethane for the LCA bushes, preferring to use a thin alloy ferrule for the bolt, and omitted the compression discs.
Later it proved to be a source of tearing on the outer face, due mostly to the subframe, and this is not easily rectified (and why 107's use steel chafered bushes in the LCA)
using a thicker alloy ferrule and machined washers, having to step them into the bush made for a well-engineered but excessively time consuming practice with no real improvement in NVH. The steering was certainly more direct, but when you can feel every stone on the road, and the wheel reacts to it, you know it's more than a few steps too far.

Finding out the factory hardness is not as simple as it sounds. Firstly, some bushes are stamped. usually 30º,45º and 75º but not always. testing an old bush yields inconsistent results.
Testing a recently installed bush ALSO yields inconsistent results. Testing a New genuine bush - yep... slightly less inconsistent, but the variation is still apparent. Most of this is to do with the steel chafer ring that is inside the LCA bush. That's there to promote stability and reduce tearing and flex. No wonder when the LCA has the tiniest bushes known to man. At least they rectified that with w201 and w124 -> models.

But this is all going the wrong way. Mercedes-Benz designed these vehicles in the 1960's. They were designed with slide rules and primitive computers. Engineering plans were on paper, drafted by real draftsmen, not some CAD dwg or dxf file.
even NC machining was in it's infancy. Noone should expect a comparison to modern vehicle engineering with all it's modelling to be remotely comparable.

There are inherent design flaws in the 107, with the subframes being the most obvious in terms of torsional rigidity and point loading. The lack of stiffness due to having no roof, and a distinct lack of reinforcing to the floorpan in the door void contributes to the flex. This is not something that can be rectified without some serious unpicking of sills and structural bracing in honeycomb, with appropriate lateral reinforcing tied in.

So without going to "extreme levels" of re-fabricating the shell, trying to make the vehicle handle without a significant increase in chassis flex and NVH is an exercise in futility.

Beyond the most basic understanding that the tyre sidewall and damper address most of the harshness, and a stiffening in either of these areas will naturally increase the 'firmness' of the ride and slightly improve handling characteristics, there is always an equal negative. In this case it is scuttle shake, and noise/harshness.

Even the most benign improvements come with a compromise.

Before contemplating any perceived "improvements" try driving a vehicle with completely factory original suspension that has been recently overhauled. You may be surprised at how capable and quiet it is, IF you can live with the body roll characteristics that these vehicles exhibited. (That was how it was done back in the day because tyres were of dubious grip level)

If you want minimal 'improvement' then new steering components and bushes, new LCA's and new subframe bushes will highlight any inadequacies of aged springs or failing dampers, at which point you can choose to replace OE or go for an off-the-shelf solution or go further and corner weigh the vehicle and custom spring/damper rates for your particular application.

Lastly, There were some anti-roll bars which help the front springs, but they are sufficiently stiff enough to transfer the torsion into the chassis where the door voids are. If you want to understand how this is possible, put a jack under one front wheel and leave the other on the ground.... jack it up until you see the rear wheel come off the ground.... the amount of twist in the chassis will most likely alarm you.
It's worse with the hardtop off, obviously. Oh, and don't do it with the softtop raised, or you'll bend the spars. Trust me.

Here are the H&R spring specs and Koni red adjustable damper specs, and the shim part numbers for the front.
View attachment 2649520
Thank you so much for all the info! That was incredible. To address some of your points, I am already planning on doing lower control arm bushings, front subframe bushings, balljoints, as well as fixing broken parts like my sway bar end links. I do intend to get a sway bars front and rear as well. However, I do not expect to turn the car into a race car, in fact I actually enjoy how it handles even with all the currently broken/aged components. I want to turn it into something that's even more enjoyable on a background, maybe not on par with a similar vintage of Porsche, but perhaps competent enough to bring a smile.

With that in mind, it was my belief that going with Bilstein parts was more proficient than the Konis (ignoring the advantage of being able to adjust them). What led you to the Konis instead? I am also afraid of my car being to low as I have an aftermarket Zender front bumper that already tends to scrape at hard angles. Have you looked at Dkubus at all?

Thank you for all the info!
 

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1986 560SL
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136 Posts
Rear ends fine. Just got old struts.

The car had 225/60s on the 15s when I got it. Little stiffer sidewall than the oem 205. Keeping the tire size. New tires this weekend.

Just put the Lemföerder joints in this week.

I sort out this 13 year old Bilstein issue for myself, and I'm good
 

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72 350SL 4.5, 78 350 Euro, '86 500SL
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106 Posts
DO not do H&R springs. As mentioned, it drops the front by 50MM which is wayyyyy to much - even with the 18mm shim. And usually the kit does NOT raise the rear by 15mm... It usually 40-50MM as well. So your car looks LAME. Ask me how I know.... Just putting in new shocks at the rear will probably get a 20mm raise in the rear as well. I'd start there before doing anything else. I stillahve to yank the H&Rs off my car and try to get it to sit right... which is all I'm really looking for.
2649901
I do agree with JoeB, a SL is a cruiser. Not a canyon carver.
 

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1986 560SL
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136 Posts
Yeah. Not interested in springs. Rears fine. Just want a slightly better ride with new struts, steering damper, and new rubber bits for the suspension. Just trying to fully and definitively decode this HD vs Comfort/Touring thing for the 560SL. We're close.
 

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380SL, Jag F-type
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1,611 Posts
You R107 does not have to have sucky handling. Simply with all bushings refreshed and bilstein yellow shocks (I did R&R back when they were used to sell them) the car has decent handling. Also steering slop is likely your steering box. Don't neglect your tires - anything older than 5 years won't offer full traction.

So yes, it is possible to make it handle decently, no you will not get it handle anywhere near what say, Miata, could do.
 

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1986 560SL
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136 Posts
You R107 does not have to have sucky handling. Simply with all bushings refreshed and bilstein yellow shocks (I did R&R back when they were used to sell them) the car has decent handling. Also steering slop is likely your steering box. Don't neglect your tires - anything older than 5 years won't offer full traction.

So yes, it is possible to make it handle decently, no you will not get it handle anywhere near what say, Miata, could do.
The 560sl actually handles pretty good for a car of its weight. I was also shocked by the great turning radius. I ordered new tires as mine were 18 years old when I got the car. I'll attack all the rubber underneath once I put her up for the winter.
 

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1986 560SL
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136 Posts
I also got clarification on what's available for shocks today. I communicated with MercedesSource and they say they offer:

Front Comfort 560SL
# B36 0524
24-005241

Rear Comfort — all 107
# B 46 1184
24-011846

Rear HD — all 107
# B 46 0511
24-005111

Bilstein says have one option, their OEM for the 560SL:

(Front) - B4 OE Replacement - Shock Absorber
Billsten P#(s): 24-005241 / B36-0524
MBZ OEM P#: 107 320 02 30

(Rear) - B4 OE Replacement - Shock Absorber
Billstein P#:24-005111 / B46-0511-H0
MBZ OEM P#:107 326 16 00

So in short, Bilstein's OEM recommendation for the 560 is Comfort in the front, HD in the rear. There's an option for comfort in the rear with the B-46-1184. Nobody seems to know about a HD option for the front which I believe is contrary to previous posts which indicated that OEM was HD in the front and Comfort in the rear.
 

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1983 280SL 5 Speed
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73 Posts
I also got clarification on what's available for shocks today. I communicated with MercedesSource and they say they offer:

Front Comfort 560SL
# B36 0524
24-005241

Rear Comfort — all 107
# B 46 1184
24-011846

Rear HD — all 107
# B 46 0511
24-005111

Bilstein says have one option, their OEM for the 560SL:

(Front) - B4 OE Replacement - Shock Absorber
Billsten P#(s): 24-005241 / B36-0524
MBZ OEM P#: 107 320 02 30

(Rear) - B4 OE Replacement - Shock Absorber
Billstein P#:24-005111 / B46-0511-H0
MBZ OEM P#:107 326 16 00

So in short, Bilstein's OEM recommendation for the 560 is Comfort in the front, HD in the rear. There's an option for comfort in the rear with the B-46-1184. Nobody seems to know about a HD option for the front which I believe is contrary to previous posts which indicated that OEM was HD in the front and Comfort in the rear.
Yeah, the problem is that Bilstein doesn't sell the HDs for the front anymore so that's probably why they said they didn't know anything. However, it is odd that their offering for the 560SL front is a Comfort. This is just getting more confusing.
 

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300 CE 24V Sportline
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996 Posts
My C124 shocks were replaced with Sachs that matched the MB reference numbers. The result is handling that, in the words of a man with 20 124s and a history of selling 124s when they were new, "Is like new. This car is new".

In truth, the car has 450 k Kms on the clock.

RayH
 

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1983 280SL 5 Speed
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73 Posts
My C124 shocks were replaced with Sachs that matched the MB reference numbers. The result is handling that, in the words of a man with 20 124s and a history of selling 124s when they were new, "Is like new. This car is new".

In truth, the car has 450 k Kms on the clock.

RayH
That sounds like a fantastic feeling! I'm definitely going to restore a ton of components in the car to try to make it feels as it did when it was new (and maybe even a little better).
 

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1986 560SL
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136 Posts
Now the final piece of the puzzle is to determine if 24-005241 & B36-0524 are truly the same part. The B36-0524 is the one that comes up on Bilstein's site as OEM, and the 24-005241 comes up as an 'interchange part'.

I read through this same discussion going on on a Porsche forum. Why Bilstein makes it so difficult and confusing to buy their product is beyond me.
 

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1987 300SL
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300 Posts
All this then begs a question, putting dollars aside, anyone know if there is any difference in ride/handling/feel between 'standard' Bilstein and Sachs shockers for a Mercedes R107. My 107 handles reasonably well, but I notice both front shocks have the outers leaning and rubbing on the inners, so I'll be looking for replacements front and back after it comes back from the panel shop
 

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Registered
1983 280SL 5 Speed
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73 Posts
Now the final piece of the puzzle is to determine if 24-005241 & B36-0524 are truly the same part. The B36-0524 is the one that comes up on Bilstein's site as OEM, and the 24-005241 comes up as an 'interchange part'.

I read through this same discussion going on on a Porsche forum. Why Bilstein makes it so difficult and confusing to buy their product is beyond me.
Why wouldn't they be? Maybe I'm missing something.
 

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1986 560SL
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136 Posts
The reason I wonder if they're different parts are the different part numbers
 
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