Just an FYI..
If you're having trouble getting a tap like the Reflex tool onto the end of your axle there is another way to fix the threads.
Thread restorer, thread restoring file, thread restoration kit..
Small files that come to a point on the side will work
There's also 5/16"-24 taps at the hardware store but price-wise Reflex is a better deal
Remember 24..
It's 24 TPI (threads per inch)
That's the side of the file you wanna use
Kingpin uses the same thread pitch
https://www.jbtools.com/kastar-2665-thread-restorer-file-8-sizes-11-24/Hardware should be standard SAE but it's a low profile (or thin) nylon locknut, sometimes called nyloc.
5/16"-24
I guessing they use grade 8 now, like kingpins. But grade 5 might be ok.
Zinc plating will keep them from rusting. Stainless might be more wear resistant.
https://www.mcmaster.com/94945a215 pic