Yeah, the medium case is a straight swap. All you need to do is shorten the prop-shaft by loosening it by the center bearing by unscrewing the collar on the splines.
Once the diff is in then, tighten up the collar again.
Funnily enough track work doesn't seem to be that hard on diffs.
We've ran an E36 M3 (euro 3L) Compact drift car for two seasons on a small case diff (4.27) and only broke one.
I've broken or have taken out destroyed loads of small cases diffs on road cars though and even one was just in a 316i last week! :eek:
3.73 LSD will be perfect for a turbo M42 by the way :cool:
I'm using a 3.91 in mine but mine is only going to be a 2.1 on ITBs and have a 6 speed box from an E46 M3 anyway
