You also need to be aware of the brg retainer size , some belhousings have the small 4.35 hole , this will work only with the small brg retainer trans , most will have the 4.80 hole this will work with both 833 trans , as if you have the small retainer there is a conversion retainer with the small bolt pattern & larger diameter or you can get a spacer ring . If you are using the OD 833 the front retainer is 5.20 " , this is an easy fix , the front retainer can be turned down to 4.80 on a lathe easily.
Whoo-boy, so much truth contained in such a small space.
Heeding this advice is preferred over the way I learned it; 2 owners before me dropped a 440 into the '73 Challenger and kept the original-to-it's-now-gone-340 small trans . . . along with the WRONG, smaller (4.35 outside diameter) front end bearing retainer!
Of course, they also used the aluminum 440 bell housing, with it's 4.80 (IIRC) opening WITHOUT removing the 4.35 smal trans fr end bearing and replacing it with the correct 4.80. "Wayne" at Brewers told me he gets "a call a week" about the eventual after effects of this ~~ people just assume that because everything bolts up and looks okay, it must be. It ain't.Hmm, .045" "slop" between fr end bearing retainer and inside of bell housing opening, not hard to do the other "math": eventually destroyed pilot bushing and slightly boogered front-nose end on my input.
Even though the inside of the trans has received a clean bill of health and several knowledgeable folks are telling me the front-nose end on my input is still okay to re-install with a new pilot bushing, I am going to go ahead and drop the $ on a rebuilt 833 1"/23-spline from Brewers.
Of course, since I'm essentially "$tarting over", I could always go up to the 1-3/16" 18-spline input but, I honestly don't know what advantages or disadvantges there are to doing that.
nr1feak, just out of curiosity, which are you going with 23-spline or 18-spline?And, what gear ratio?
Heck, I haven't even decided which of Brewer's gear ratio offerings I'll go with yet but, I am only looking for street use, occassional hole shot with the grandson in the passenger seat (he smiles SO big! ;-). No racing, etc.
I sure credit you (might even say envy) you for asking such a great question before stepping into the fr end bearing retainer "pothole".
Best o' success!