most issues I have seen or had have been the pinion nut coming loose/pinion bearing wipe out/crush sleeve adjustment or lack of.

every one I invested in got a new set of bearing and set up with shims and solid spacer. never issues after that with them.

I prefer the 8 3/4 for gear change and I can run non adjustable green bearings and Moser axle any size needed.

30 min R&R and either a 2.76 3.23 3.91 gear ratio under my bench.