Great upgrade for 5-speed E36's out there with the 3.15:1 diff. This 3.91 is stock, from a 1995 325i w/ 130k miles and automatic trans, replaced because the owner thought that was the source of her noise (it wasn't). I'll throw in new BMW Synthetic gear lube for free once I have a buyer.

$250 over the counter, or $400 installed.