How to

You have to pull the axel out of the differential , and this involves a lot of work , such as taking the inspection plate off of the differential and partial disasembly, if you are set on tackling this repair i suggest you buy or borrow from the library a repair manul for your BMW, the barrings are pressed on and you will need to take the axel to a machine shop that has a press to remove and replace the barrings , this can be a fairly complicated job and i don't suggest it to a novice

There are three type differential units listed for your model BMW and one is a positraction unit.
A differential overhaul is best left to a qualified pro.