One tonner tailshafts could have standard V8 uni's same as V8 cars, utes etc. (more common in 6 cylinder tonners) or larger uni's with caps similar to 9" diff uni's. There is a spicer part number something like 2520 for the tonner ones like in pic. Not good memory!! You can get a adapter uni to fit larger cap back to standard that works well. It looks like a normal uni, but has 2 larger caps & opposite 2 are smaller. I have used these several times without any dramas. Probably easier than changing tailshaft or pinion yoke. Can chase part number if that helps

cheers
Max