Whayden, MOPAR made many variations in the transmissions and there for the Bearing Retainer. You need to read the A833 history on brewer's website.
I won't say all, but the Truck OD units I have seen take the big 308 bearing in the input gear. The early A833 used a small bearing (307). Mopar also made a change in the tail shaft bearing, again going to larger for the hemi versions and the overdrives.
You can move parts around on these you, so you need to inspect what you have. Cast numbers on bearing retainer, case and tail shaft are needed.
A common mod I have done is to take the gears out of the Aluminum OD case and put them into a Cast Iron case which gives you the look of an original A833 but with OD gears.
Racers like to use the Aluminum housing to save weight, so they would go the other way. I just bought an OD that I plan to put close ration A833 gears in.
Here is 2 bearing retainers. One is an original from a 70 up BB A833. Has the larger bearing cut out (308) and the 4.16" bolt pattern. The second one is the standard bearing retainer from an OD Truck. It started as 5.125" OD but with the same 4.16" bolt spacing. It was cut down to 4.8" and is a match now for the original piece. The middle picture has them stacked on each other so you can see the hole line up.
Ignore the fact that the original is sleeved for a hemi large throwout bearing.
The anomaly I don't know as much about is the A body late model OD trans. I think they had the same bearing retainer just a short tail piece, but I am not speaking from first hand knowledge on that.
