Do you have the propper tools?...
There is just about no way less you have the BMW plate for axial play adjustment... Red-neck plates can be made from gearbox rear-end-covers.
Motorworks in England used to sell such - perhaps they still do.
IF you get the play too tight... you will need a new gearboxhouse...
If too loose is not as bad though, but wear will be more rappid....
IF one of the bearings breaks... the gearbox can litterally explode... Oak Oshlen have written about this, and an aquaintance of mine have experienced it first hand. When it explode it can rip off the lower leg on the side it bursts on.