Pulleys overlapping?

Jadaharabi said
Correct me if I'm off a year or two.
71and back had one bolt hole that was not concentric.

72 + on the bolt holes were evenly spaced this is on the crankshaft pulley I'm talking about.

I thought the change was for 71 and up but it could be 72 but yes, you have the just of it.
Never could understand why they indexed the pulley.