I have talked to no less than 4 owners of 190 series Mercedes all selling their cars for cheap because the transmissions are blown.

Why are these transmissions so weak? I have a friend willing to sell me a 1985 190D for cheap, but it needs a new transmission. I have no idea where I would source one, and if I do, and the transmission design is inherintly weak, then I will probably be installing another transmission some time soon.

How easy would it be to convert to a standard transmission - assuming that I could even FIND a standard transmission complete with pedal and everything.