So far I see that people seem to do one of two things:

1. Grind out the peened part of the nut and then reuse the nut (I don't get how this works because if you removed the peened part, what's preventing the bolt from twisting?)

2. Buy some 280ZX nuts with a "ripple" in the threads. Not sure how that works because I imagine it'd deform the stud.

Anyway, anything I'm missing here? Are those my only choices? Thanks!

The 280ZX are your basic "deformed thread" lock nuts. They won't harm the studs, they're designed to work with them.

You wouldn't re-use the nut, you'd get another and peen it over again. The ZX nut is the best option and won't hurt anything.

Thanks for the info. I'm not very familiar with those types of nuts. Just for future reference, they're not reusable?

Many people reuse them. You can tell when you get in to the locking part of the thread, it gets much harder to turn. Other nuts on the car are self-locking also, like the ones on the two long transmission cross-member bolts. But, the FSM recommends a new nut. On the axle, probably best to go new. You can still get them at your dealer, I believe.

They even show up on the Nissan data base. $4.98 each.

Rear Axle :: 280ZX Parts (S130) 1979-1983 :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

Awesome. Thanks!

I hope others find this helpful in the future too.