So once up on lift it turns out there is a fair amount of play from the motion of the (new) prop shaft and take up of the half shafts so whatever internal workings are between those components would seem to have some wear. Additionally, the gear box gives a lovely 'slap' when going into fifth. Question, is it worth a diff rebuild (Rimmers have new CWPs but not sure if they are remanufactured jobs) or live with it and wait for something to drop off? :-/