Hiythankyew
My vote goes to a knackered diff housing then.
so it would seem i was correct the pumpkin is u/s.
If you look at the ring gear does it have an even wear pattern across the flank of the gear teeth?If so, that's good, if not, and there is local pitting or heavy localised wear it could indicate the pressure angles of the ring gear and the pinion are different and therefore not meshing correctly or that the diff housing itself is distorted.
How would diff housing distortion lead to pinion bearing preload loss ?