"Big block" A833 close-ratio main cases with the 308 front bearing have the same bearing-retainer bolt pattern as the A833OD (which also uses a 308 bearing). That means you can swap the large (~5.1") OD retainer onto any 308 case. I have a friend who did exactly that. He's using an A/F-body overdrive bellhousing with a '68 383 transmission in a bench-seat '73 340 B-body. You use the fork for the bellhousing application, not the car.
Just pointing out that there are options other than the overdrive transmission with this bellhousing.
Conversely, of course, putting an overdrive behind a big block is just a matter of swapping to the 4.8" retainer. It's a 5-minute swap.
