Broken rear end(ring pinion)

[Ivan141]

Yes, but the pinions position relative to the ring gear is supposed to be firmly fixed. There shouldnt be much flex in a diff.
I have bought a solid spacer myself, but havent used it yet.

Look it up on some 4x4 forums.. the guys that are seriously into this hobby all swear by solid spacers. If anyone abuses their differential, it's those guys.
The original crush collar design is there to make the production of the car easier. No adjusting shims necessary etc. If it gets overcrushed for whatever reason at all, the pinion will sit looser, and this is not a good thing.

All that being said, I think you'll still destroy enough gearsets. The 6.7 inch diff on an ae86 is pretty small, and the higher the ratio's become, the weaker the gears become.