I think 5x8x0.2mm shims would be the correct size, but if the issue only happened after servicing the diffs, I would wager something isnt seated correctly- should be simple enough to eyeball the issue, or feel for it if you remove the diff and rotate each shaft seperately/ together- if its 'popping' in a certain place, then the ring gear is my guess at the problem, but id its doing it consistantly as you rotate the input gear shaft and hold the outputs still, then some shimming is needed probably.
Kinda hard to talk you through it though, its one of those things one would fix by sitting and playing with it for a while and trying a few things until it works correctly again*
*feel free to make a rude joke out of that one Linc
