I've been doing some reading on diffs and LSD's lately and found some good information.

Hopefully of use to a few on here:

A very good guide to how to rebuild/build an LSD

http://forums.bimmerforums.com/forum/showthread.php?1650106-The-E36-Diff-Thread

168mm LSD technical discussion and internal setup overview

http://www.r3vlimited.com/board/showthread.php?t=291569

Swapping E36 168 LSD internals into an E21 case. (Reverse should be possible?)

http://forums.bimmerforums.com/forum/showthread.php?1565138-e36-lsd-internals-fit-into-e21-case