I own a 1982 240D, U.S./California specs that I bought used in Naples, Italy (where it and I still are). It has an automatic transmission which need rebuilding, I think, as it used fluid at the rate of paint every couple of days, and it won't stay in 1st,2nd or 3rde without keeping the gear selector out of drive, nor will it kick down, except at a stop. I would like to know if it is possible to replace the automatic with a manual and if there is an MB 5 speed that will fit this engine. I think that on some cars the transmission end of the crankshaft is a different size or configuration for the automatic vs the manual. Is this the case for the 240D?

Thnaks for your help!

Yes the manual trans will work, but you will need another car to get all of the different parts you will need.