so the bolt snaps in half and shooots into the differential and destroys the diff, does anyone know were l can get a used one for less than 2000 bucks, websigts or anything

bmwcca.org, The BMW Car Club of America, if you enjoy having fun with BMW is this is the place to go. Many members sell used parts and many new parts suppliers will give you special offers and/or discounts.

This shud not happen in BMW,unless someone has done some modifications or a different model diff being used.Is the rubber couplings in place fro, drive shafts.
or u bearings broken n shifting the drive shaft load onto the diff? check this before damaging another diff.

i can get u one & also l have E34 diff
it will cost u about 1500 bucks from importers (a real good one)
and mine l can give u for 1200 bucks,
Give me proper details of the car.yr/model.auto or manual.
where do u live.?

Ahh u been bad.. Yep they do that.. As u may know the M diff is an oddball. I've been where ur at a time or two. l found the only way to deal with it is to rebuild the old one. So far every time l dealt with the ring & pinion was ok. Some l was able to just remove the rest of the bolts clean it out good & put if back in the car & change the gear oil 3 times sometimes 4 every 500 miles. Some l have had to replace the bearings. Changing the bearings requires a spreader tool so l have to send it to a machine shop.