Vintage transmissions are not like the newer ones. There are upgrades that have to be done, and special tools needed, so that the transmission will work right.
A shop that rebuilds newer transmissions doesn’t know their way around the older ones. Don’t let the late model shop experiment with your transmission. I have fixed transmissions that other shops have worked on multiple times. Don’t get stuck taking your trans back and maybe never getting it fixed right.
I have been rebuilding the vintage transmissions since they were current (over fifty years). I learned on them. They are not new to me.
I have over 50 years experience in rebuilding automatic transmissions. I learned to be a rebuilder on these early transmissions and rebuilt them when they were common.
I would like to put this and other things in, and some pictures.
American Motors 1962-1973 T-35 trans, Flashomatic, Flightomatic