Well, my 1997 C36 began having slippage problems in the tranny at 118K miles. The clutches would slip between 2nd and 3rd, the engine happily revving... with no drive. I had to shift by releasing the throttle and let the gears engage under zero power.
So I had it rebuilt by the new Orange County shop (O.C. Benz) that was formed from the ashes of what used to be Bruce Strauss Autocare in Costa Mesa. There, Jeff and Ron bebuilt the thing. The clutch plates were worn and uneven, and the fault was of the inadequate (but now upgraded) shifting module giving all-wrong signals, eventually frying the clutches. These modules can be rebuilt to current standards and they are a specific AMG part ($220.00 cost). Now not only does the trans shifts perfectly (and very smoothly) but the engine functions that are directly related also make the car much better and quicker than before. The cost of full rebuilt was under $3K for the whole mess, not too much considering that I paid so little for the car to begin with.
What am I left with? For a total expenditure of about $16K, I basically drive what amounts to be a brand new car able to clean the clock of 90% of whatever is on the road, while being comfortable and incredibly safe due to the very good handling and brakes.
I also love one thing about this car: this is the first car I ever had (besides my actual vintage racing cars) that wears its four tires perfectly evenly, none of this Bimmer inner side wear in 8K miles! That shows perfect bump-steer geometry. I have some very quiet Kuhmo ZR tires, much quieter than the Michelin Pilot, at less than 1/2 the price of the French skins. The grip is about 95% of the Mich' and it is plenty sufficient for me, I can do with a bit of slide at the limit, I like it.
If anyone in O.C. has tranny problems with their C36/C43 with the electronic 5-speed, please pay a visit to O.C. Benz on Bristol street, those guys DO know what they are doing, and I have dealt with them for over 25 years without ever being disappointed.
PM me for more info, those cars are worth keeping until run into the ground.