I am having problems with my 1990 525i. It has a M50 engine and an automatic transmission. The transmission starts out in 2 or 3rd gear. Once I reach high speeds it seems to drive ok. Even when I shift it manualy from 1 to 2 to 3 to Drive, it still stays in the same gear. I am wondering if anyone came tell me if a M20 transmision will fit an M50 motor?