Looking at your ball & trunnion driveshaft coupling face I am wondering if there were two different ones...one for auto & one for manual? The below photo is of my current piece that was on the trans that Keith Long built for my 64 Sport Fury 426 console auto. You can clearly see the matching indentation for your ball & trunnion face.

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Last edited by dmoore; 10/28/20 01:00 PM.
https://www.forbbodiesonly.com/moparforum/showcase/1964-sport-fury-convertible-426-s.5390/