Are these the right lower A arms?

This discussion got me to go look at my LCAs. I have a left and a right (as per stamping) that came from '73-up A-body out of a salvage dealer. Didn't notice until now that the pivot bolt is slightly different on the two arms. One has a barrel style shoulder, and one has a tapered shoulder. See pics. Did they come from different cars, different year???? I don't see a problem using either one, but now I'm curious why they're different.

LCA LH.jpg LCA RH.jpg