Sta-lube gl4 85-90 in mine as well. NAPA carries it here in Florida. Wayne has it at Brewers Performance as well.
Sta-Lube GL-4 here as well, supplied by Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists
Great. Make sure it's GL-4, not GL-5. Lots of stories online about adverse results with GL-5 and our transmissions...
Most of my 4-speed experience is with Muncie's and Toploaders and I've just recently acquired an 833 in a car - but I'm always amazed at reports of running motor oil in one of these old 4-speeds. It takes a lot of effort and care to re-seal one of those old transmissions to where it will hold in 85-90 gear oil. Motor oil in an old aluminum Muncie with a worn countershaft bore would probably be nearly dry of oil in a day or two. And my Toploader I've rebuilt/resealed a couple of times and it still has an occasional drip. I guess if you can get an 833 sealed up good and tight then go for it. Another vote for GL4 Sta-Lube from NAPA.
I had a little gear clash when cold from 1st to 2nd. Sta-Lube did nothing, but the Penzoil Synchomesh worked like a charm. Shifts like butter now.