Let's not confuse bearing retainer size and bearing size. There are large retainers for 70 SB but with Small input bearing. SO the AAR/TA 340 also had a 307 bearing not the 308 as input?
The 70 SB had the smaller 307 bearing AND the smaller bearing retainer od. The 70 383 had the 308 bearing and the bigger od retainer. However. You could take a 69 383 bearing retainer for a 383 with the small 307 bearing and big Od and install it on a 70 SB trans to fit a 383 bellhousung. You just can’t take a 70 383 trans and install a SB retainer because it has the 308 bearing. You can if you use a 69 383 case. Yes the TA/AAR had the 307 bearing.
