After having the diff dropped out twice, bearings replaced, etc, the diff was still whining when you lifted off the throttle. My "shop" put my original OEM crown wheel and pinion back in (I was running the 4.08 FD) and all was good and quiet. The (damaged) 4.08 pinion was put between centers on a lathe, a dial indicator applied and guess what? It's slightly bent and therefore not running concentrically which was causing the whining noise! All this because I ran over a bit of light gauge RHS steel tube that had fallen off a truck or something!
I have now ordered what will be my second 4.08 FD set! I've yet to try an insurance claim
