Didn't know you were watching LEVE!
Yup, made more than a few of those down through the years, on everything from lawn mowers to earth movers!
I have one in the shop somewhere that has a 2" square drive hole in it! Guess what that's for!?...
The gear and it's threads are usually pretty hard steel, but the nuts are usually pretty soft stuff.
I've stripped more than one nut myself.
Yukon seems to have crush sleeves that are just really hard to get them to break over!
Wiped out two nuts on the last set of Yukon gears I installed before using the nut Yukon sent (it held, but I don't like using the new nut to crush AND to torque...) and it held (knock on wood).
If the nut backs off after coming loose, and is inspected for damage, you should be OK with lock-tite, but this is one place you don't want to skimp on a few bucks!
I get a new nut with the gears, from the gear manufacturer when they will cough one up...
Use the old nut and molly lube to crush the sleeve,
clean off the threads really well, and use the new nut with lock-tite for final torque.
You already know once the darn sleeve crushes, it doesn't take much to do the preload!
Seems like one or two companies are sending out some really stiff crush sleeves...
Maybe someone should contact the manufacturer and let them know they might have a extra tough batch!
Who made the gear set you are having problems with, and did the crush sleeve come with the gears?
If not, where did the crush sleeve come from?