I have a 76 Dodge that I have owned since 1980 and have always used Wolf's Head 80W-90 Hi Performance HDX All-Purpose Gear Lube. I live in western PA, but the van is only driven during the summer months, so the "warm climate use" don't apply to me as pertaining to the ATF fluid.
Thanks for the replies regarding oil, I decided to go with the factory recommendation of Dexron ATF. I will see how it shifts and sounds, it does have "150k on it, so it may like the thicker stuff.