The e30/36 bearings will come off perfectly cleanly and unmarred with the correct tools. Minimal force required also. Zen approach style.
Are you using a 168mm or 188mm LSD unit?
The e46 cases are narrow compared to the earlier units, the ring gear is more centered for bearing load-
To fit a 188mm earlier chassis diff into the e46 case requires clearance-ing the case. Aftermarket LSD installation (OSGIKEN,Kaaz) requires minor grinding, installing a Oem earlier car standard unit is more than minor grinding. Older lsd 188mm units have almost no clearance in a e46 case. Replacement parts for these diffs are avail from ZF engineering in Germany, parts are very expensive.
The spacing gap difference between flange geometry also needs to be made up. If using a 168mm unit then the bolt pattern/count as well.
In the end of the day it's adapt-able yes and some builders do it. I prefer doing a OSG or Kaaz install keeping 188mm or going to the 210mm e46m diff unit. 3.07, 3.15, 3.23, 3.46, 3.62, 3.91, 4.10 and ++ are all avail in 210mm standard. Two bolt patterns of hardware create some expensive compatibility solutions.
If you are dead set on retroffiting an older Lsd center to newer case
I'd suggest starting with the 168mm unit as more clearance will be your friend, A spacer is needed regardless. Good luck on the mounting fasteners!
Building up an Oem bmw LSD is required as dumping a ancient rotting smelly 20 year old LSD into your prepped grippy tire e46 is probably not going to be a long lasting solution, e30's can easily wear out their stock LSD units. Refresh and rebuilding the internals of the LSD unit is a cool $250 in just parts. Add that to the core unit cost+ labor and perhaps a brand new quaife LSD is not such a bad deal after all. Kaaz is not a very street friendly or economical diff, I just removed one from my own car.
Last edited by wanganstyle; 03-30-2012 at 01:11 PM.