Again, THANK YOU for sharing this data! I have a 1977 727 which I would like to swap in for the 1966 version now behind my 1966 383. I see from your issues that at the very least, I need a torque converter which will facilitate this transplant. I too had considered swapping input shafts, until I saw your more recent posts. If I have some issue arising in the future beyond trivial maintenance, I hope that by sharing the tale here I can help some soul as much as you've helped me.