What fluid for a 4-speed trans?

Another vote for MT-90, while I haven't run it in an A-833 I did run it for years in the AX-15 5-speed in my Jeep and it made a big difference in shift feel and effort the first time I put that fluid in it (had 180k miles when I first got it and I put another 80k on it myself, never rebuilt). That trans has brass synchros like the A-833 and there aren't that many different ways to make a manual transmission. Newer ones just have internal rails for shifting and the synchros are made of different materials and may have multiple cones on the lower speeds (Tremec TKX, T-56 etc), that's about it.

I do remember it being a tad sluggish going into gear when it was really cold (below 15 degrees Fahrenheit or so) but after a few minutes driving was fine.