I have a R31 rear end and one side you can move the hub in and out about 1 - 2 mm, whilst the other side is fine.

I was thinking that the oil seal may be worn and thus when you tighten up the 4 bolts to hold the axle in it is not applying enough pressure to the bearing?

Or the bearing retainer has not been pushed onto the axle far enough.

Or the bearing itself is stuffed?

So maybe a new wheel bearing kit would solve the problem and eliminate all 3 ???

Or is this amount of movement acceptable for the R31 diff? Dont know if these are the original bearings, the good side has hammer arks on the bearing retainer so I assume that side has been changed at some stage.

Cheers