From what I've been reading, the OEM axles are considered better than aftermarket.

What part is better exactly?
Rzeppa joint?
The axle shaft itself? (apparently aftermarket ones are the wrong length?)
Tripod?

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Background info. I went through my Muncie 4-speed with new seals and bearings, and I have about 7k miles of use since then.

Since the beginning, the axle seals have always wept a small amount of oil.

The seal journals on the tripods were grooved, and not very shiny. I decided to run that pair of OEM axles as-is.

I'm wondering if I should focus on repairing the stock tripod journals (sanding/polishing, or speedi-sleeve), or if I can simply swap over a pair of tripods from new/rebuilt aftermarket axles and end up with something good.

I have found that all OEM axle are stronger. Aftermarket tend to use parts that will work across more car lines.
Example: most of the time you would not be able to use the center section of an OEM axle with after market joints or the other way around.
I recenty had to make another axle for the right side of my 3800n/a,4t60e swap. I could use outer joints from a manual Fiero or joints from a N-body(grand Am)that had a 4T60e. The inboard could be from any 4t60e right side. And the center section had to be from a W-body(Lumina, Gran Prix) left side. The after market parts would not work.
Also I have been working on cars since 1980 and have found the aftermarket parts to be of lesser quality.

I had a similar issue on my Getrag 5 speed. Here's what I did on mine several years and a couple of thousand miles ago and all is still good.

https://www.fiero.nl/forum/Forum2/HTML/140014.html

Sounds like OEM in a general sense is better, and I might not be able to swap an aftermarket tripod anyway.

I'll stick with trying to restore my stock axles!

My diff bearings are pretty new, so I don't think the stabilizers would help here.

I was actually messing around and made a video yesterday with some info that may help you. I just a tripot replacement on my axle.

https://www.youtube.com/watch?v=dYPqy21dwpI

I took my axles' tripods off maybe 12 years ago when I replaced the boots, but that was a good refresher!

Check out cvsource in buford Georgia. They do complete R&Rs on OEM axles, and OEM only.... He's done two of my Mazda 6s 5spd axles that are no longer made by Mazda. I spoke to the owner for about 45mns on the phone and his knowledge of the oem, performance, and Chicom axles market is down right impressive.

He was able to look up the metal composition of my axles and as part of the restore process, I thought mine was fine except for a torn boot but I wanted it overhauled, they tig fill the grooves in the tripots with higher grade steel then remachine to tolerance. 135$/axle plus shipping..

He gave me lots of info on DSS too...very very informative...

There was a guy in our former club that did a SBC V8 Archie swap, and on his first 1/4 mile run, he snapped a Chinese axle in half. If you ask me they are of very poor quality.

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Are used axle tripod cups considered interchangeable?

Or, is there some sort of "wearing-in" that happens, where the cup should stay matched to the tripod (possibly clocked with the same sphere in the same slot) it was used with?