Auburn requires specific axles, or at least minor machining of axles not designed for the Auburn diff....I think the difference is a tapered edge on the end of the axle that slides into the differential.
Well, mine has had the moser axles and the auburn for quite some time.
And when i purchased the axles i didn't go out of my way to purchase anything specific.
31 spline moser axles, 5 lug, fox length. That's it.
And the last time i had one out was for a rear disc swap, and i don't remember any tapering.