[diametricalbenz]

Many have done this conversion, it's entirely doable. You have to balance the crankshaft and the flywheel together to make it proper but some have just bolted it on. Some have had vibrations in the low 2000 rpm range up to 3000rpm as a result of harmonic problems. The driveshaft has to be used from the 240D since it is longer but either way the shaft has to be cut to length and balanced. The shifter rods will also have to be cut 4" or so to accomodate the same distance back due to the extra cylinder.

 

[diametricalbenz]

this isn'y supposed to be fast i just wanted to be able to tow my boston whaler with 170lb ft tq and be able to change lanes on the freeway

Towing? A Boston Whaler? Seriously? Unless you have a very tiny whaler you're talking a boat that weighs quite a lot plus a trailer.....~2000lbs? I never got a scale weight but we used to tow 17 and 19 foot whalers in college pretty much every week.

In a car that may puts out 120lbft not 170lbft (that's the turbo spec) when it was brand new....

I wouldn't want you to be dissapointed.