Most of our rigs have more than 75k on 'em. Yeah the bearings are likely still good but they do fail, especially the pinion bearings. You are likely to put more preload on the carrier bearings too, to minimize ring deflection. Easy to get back in there, but on the trail, not so much (DAMHIK).
I like spacers. High loads don't change the preload so much as slightly over crush the crush sleeve resulting in a loose pinion nut over time. But really, no idea on the frequency of incidents. Lots of guys like the crush sleeve fine. Given a long enough cheater bar and solid vise, I find them easier. Just go slowly on upping the preload. Multiple pinion nuts not needed due to boogered threads.
Heb Dduw, heb ddim; Duw a digon
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