I'm building a twin turbo M103 in a 1990 300SEL. I also have a 1991 Corvette which is getting an LS7 and T56 upgrade so I have a donor ZF-6 transmission. In stock trim it is rated at 450 hp which is plenty for my needs. The interesting thing is that the car came standard with a 700R4 automatic. The ZF-6 was an option from the ZR-1 of the same year.

So if the adapter kit we are talking about accepts a 700R4 then my ZF should be compatible. The big question I am trying to answer is whether the OM60x motors share the same bell housing bolt pattern with the M103/4 motors.

I also have a call into Sun Valley Mercedes Transmissions. If I can determine that the 722.3 versions for my car and say a 350 SDL are the same then I think we are home free.

I wish I had some of the fabrication skills that others have shared who make their own bell housings but I don't so an adapter kit seems like the most straight forward way for me. If I can definitively determine that the inline diesel and gas blocks are the same I will share that info.