Brewers has them new. Used gears may look good to the naked eye but there are 9 teeth that hold it in gear when you leave off the throttle. If worn is very hard to see. Just went through this with an early trans and Dan from brewers transmission helped me out and schooled me on it. unless they drove the car the gear came from how would they know its good. I believe they can be reconditioned
"I believe they can be reconditioned"
You got that right. I have reconditioned many, and in all vintage makes.
In fact, all the gears in my early-60s Commando box have been reconditioned, and the sliders as well, and some, more than once.
However,
Since I have many years experience doing it, I am reasonably confident, that I can easily recognize trouble spots. A833s, IMO, are one of the easiest (next to the Saginaw) transmissions to work on, and the gears are seriously robust. The clutch-teeth can be doctored many many times.
My Commando is about 60 years old. My 2.66low, is about 56 years old. My od-boxes are early 80s. AFAIK, there is not one un-original gear in any of them. Sliders I cannot swear to, lol.
Brass rings on the otherhand, I keep spares.
Cluster-pins from A833-transmissions running ATF are probably the quickest wearing parts. But the pins can be turned, re-keyed, and reused, with new rollers.
Transmissions running ATF, shift much faster than with 140EP
In between multi-grades are a good compromise.
Many years ago, I switched to 50% Dextron-II/ 50% midgrade EP. This has worked out well for me, with long cluster-pin life.
I long-ago abandoned synthetics for this application. For me they just shifted too slow.
In a trans that has run synthetic, and you wish to go back to EP, sad to say, IMO, the Trans will have to come down, be disassembled, and be thoroughly washed out and dried....else the synthetic will corrupt the new oil , and results will not reflect properly, the capability of the new oil.
While the trans is apart, on mine, I modify the cones to shed oil faster, and to bite harder on the brass. And of course, I slick-shift Second and sometimes Third. When this is done right, the guy on the shifter can easily overpower the brass, and the beastly A833 can shift as fast as anything. And yet, having left the brass in there for street-duty, you can granny-shift it too. Win-win. Oh and, the brass lasts nearly forever.
These are my experiences, and opinions as noted. Your results may vary.