I think this might be the info your looking for. I hope it helps. http://www.bigblockdart.com/techpages/4sptech.shtml
It is an article about beefing up an 833/833OD for big block apps. Good luck with the build.
....Also be aware that the 1966-67 A-body 4-speeds and some mid -70's A-/F body overdrive units used the small (904 size) output shaft and slip yoke....
I assume this means not all of mid 70's the A/F body overdrives got the 904 output. So there are overdrive tailshafts that have the 727 output? Are those aluminum??
