QUESTION FOR UCA BALL JOINT SEPARATION

Sure
The early BJs have smaller bodies and pins. They only fit into matching UCAs and matching knuckles.
The 73up stuff is bigger bodied and larger shanked except the 9"drum stuff, which was a carry-over from the earlier style.Some say it mightof continued into 74,IDK
BTW, I've heard it said that the only difference in the UCAs, was the joint receiver.And I've also read about adapter bushings made to fit the small-pinned early BJs into the later large-socket knuckles. I haven't seen one.