Hey HC, long time. I run into this problem on all rebuilds. The new output shaft fabric thrusts are supplied to thick. I do a lot of tranny work and save all thrusts removed. The ones I like to find are the old brass ones. It is possible to hand fit with a sliding glass with emery of different grades glued to it. Another issue can be with the tabbed spider thrusts. There can be a little lip where center hole was punched. I position them on the shaft with a old gear and tap on them in hopes of shaping.

There are also two different diff. output shafts for pot joints. One has a flat surface and the other a shoulder slightly proud of the gear face. I think some go without a thrust block.

As you work on clearance they will feel like clicking as you turn them different directions. I don't put the spider shaft pin in till I'm happy with the fit. Steve (CTR)

The non-gen fibre washers can often be too thick (like Specialist), I've resorted to using old ones in the past.

Rebuilding a rod change box. On the diff I have a new diff case, pin, and thrust washers. When I put the diff together it binds up. The gears wont rotate. Anyone ever had this problem? It seems like the small thrust washers are too thick.