Not to steal the thread, but have a question... just acquired a 81 240D with the 300TD conversion, runs great 4spd car..also got a replacement diff from the owner which he states are more highway"friendly" gears.

I drove it home about 60 miles and agree a 5th gear or higher gearing in the rear would do it some good.

My question, what gear ratio is stock, he believes this set is 3.32 but I havent got any numbers off of them yet.

Looks to be a pretty straight forward swap.