'63 manual trans engine swap with '74 automatic

Thank you for a quick answer and a very helpful link!

It appears the main thing I need to confirm now is what year 904 automatic is in the '66, as it appears that the torque converter hub needs to conform to the crankshaft hub recess.

Hopefully, the original '66 trans was kept in place and a spacer used to center the converter hub, so then I can just remove the spacer and bolt the automatic to the '63 engine. If I understand this correctly, a later large-hub style 904 cannot be made to work with an earlier engine, as the earlier hub recess is smaller.

Time to crawl back under and look at some numbers in the trans!

Again, many thanks to this forum!!