LBJ upper control arm question

The ball joint is bigger and the diameter is larger. Take an old SBJ control arm for comparison. The smaller ones are more prevalent, as the
big ones are usually 73 and up.
No I'm aware of the difference but I'm not home to take a SBJ arm with me. I'm going to a swap meet and was trying to figure out if there was a way to tell by looking or a measurement I could use.