Dave,
That Universal Joint Ball Housing Seat on eBay has 5 holes and it is for a 29-50 Chev/GMC and 33-36 Pontiac. Is the 5th hole for a Pontiac? Four of the holes look OK for GMC/Chev. Also, if it works for 29-50 Chev/GMC, shouldn't it should work for 29-54 (except Powerglide and Hydra-Matic).
It looks nice in brass. Is that item the repair-piece that goes inside the rear of the transmission (probably a stupid question)?
Thanks,
Tim