Yes, any W201/W124 trans will work with the 603. Gasser or diesel, it doesn't matter. Yes, the flywheel to crank bolt pattern is the same, and all of the cranks are pre-drilled for the input shaft pilot bearing. There are 10 bolts that hold the tranny to the engine. Some of them are pretty tough to get to with the tranny in the car, you need a couple of long extensions and a u-joint for your socket set.

The tranny crossmembers are different for the automatics and manuals. It's best to get the correct crossmember, but the automatic crossmember can be modified to work with the manual trans.

Shifters, pedal clusters are a 100% bolt in affair. The holes are already there for the hydraulic line between the master and slave cyls. You would need the brake pedal switch from a manual trans car. The switch is different between manual and automatic. The nuetral safety switch wires attach to the clutch pedal switch. (you don't have to use it if you don't want to). The back-up light wiring from the automatic trans hooks directly up to the shifter on the manual trans.

If you do it once, you will know the MB system like the back of your hand also.

SteveM.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner