RMCHRGR
No, The Ball and Trunion was on the 64' cars and the change over to the slip yoke was in early 65' sometime more or less. Maybe even very late 64'.
My car just slipped in the door during the production run to have the slip.

Interesting news on the lightweight cases over at A&A.
Cool addition to have pressure adjustment access.

On another note pertaining to adding weight, my late 60's tail shaft housing is a little heavier (less than a pound or so)then my 65' tail shaft housing because of the extra webbing introduced into the casting for strength.

I sure wish I could get access to my motor block motor mount ears and bosses to remove that dead weight. It must be at most a pound and a half right there. Next time the motor comes out for sure since I run a plate and don't need no stinkin' ears. Aluminum plate that is. LOL.