1999 M3, Diff blew up. Ordered another 3.23 from a Convertible M3 and sent to the shop where the Bimmer is getting fixed. Very well educated shop and they have been dealing in Bimmers for a long time. Shop manager calls me today and says the Diff that I ordered doesn't fit because the "so-and-so" is too long. I know that's kinda vague but I can't remember what he said to save my life. In figuring this out I just wanted to know if there are any differences between M3 diffs I should know about so I don't order another wrong one. I'm just kinda hoping they're making a silly mistake and it really does fit and my M3 can be back on it's feet after two weeks... :( Wishful thinking. What should I know before ordering another one? Thanks guys.

Just called the shop to ask again what the difference was and he explained the "input shaft length" on the 96 diff was too long.