So I took an 09 500fm rear diff apart trying to find my rear end problem. Everything inside looked fine, and I discovered the problem was a broken you d and I discovered the problem was a broken ujoint. Got a new ujoint ordered and tonight when I tried to put the differential back together I can’t tighten the diff bolts without binding the Pinion and ring gears. There is one shim on either side of the ring gear, and I did not remove the Pinion.

I had a similar issue with the front differential a couple years ago, and the pinion gear had walked forward towards the ring gear. I don’t see how this pinion could have walked out, and everything was fine and turned smoothly before I took it apart. I suppose I could double shim one side of the ring gear to space it away from the pinion but I know that’s not the right way to do it.

Bearings are tight, seals look good, fluid was fine, ring and pinion look good. What am I missing here?