I saw 5 gallon pails of 80w-90 gear lube at advance . Might have seen gallons too. Five gallon seemed like a good deal, compared to quarts. Probably a worthwhile buy for the younger members.
As for brands, it’s just Hypoid oil. Has anyone ever torn down a failed gearcase and said "Damn, he used the wrong brand of oil"? No, they say "where did all this sea water come from?"