Alu OD 833

Earlier the better. 75 "A" body or "F" body should be good, shifter and all. If you are lucky, it is possible to get one with the smaller 307 front bearing. Then all you have to do is swap the front bearing retainer. The aluminum main housing has a floating countershaft, read sloppy, that can loosen up even more with usage. Try it and find out how she runs. Dump the ATF and put in 90 wt gear oil. I skip to a 64 or 65 cast housing and a new 64-65 countershaft to get everything tight again. Good luck.