Would a 3.62 rear diff from an E46 fit..

[geoprz]

Looking at an rear diff from an E46 M3 part # 2282480-06/ESB93S

Would this swap in to my 2001 E38?

[tjpike]

short answer no, long answer yes.

It won't bolt in, but if you're willing to fab up some mounts for it along with having a custom driveshaft built, sure, it's possible!

[RVAE34]

Your best bet is to narrow the diff mount locations on the subframe to fit an e39 m5 diff, use the 750 axles and then swap the 3.62 ring and pinion gear from the e46 m3 into the m5 diff. The gear set is a direct bolt in to the m5 diff.