No one usually changes transmissions themsleves, but the diff. Stock 328 diffs are retardedly long final drives. 2.93 I believe..?
A good way to go is with a 3.46 final drive out of the 320i.
Thanks for the reply I only asked because I have a BMW 318 and a freind us selling a 328 auto and wanted to no if I could biult his engine to my drivetrain