Thanks for the pictures! They show some great details.
Hans' and Len's pics both show the flat top 3.
Len's 2nd and 3rd pic each show one of the perimeter spot welds.
Len's 1st and last pic each show what looks like 4 protrusions on the edge of the inner cup.
So I guess my observations from the pics are:
Flat top 3's, 4 protrusions 90 degrees apart on the back edge of the inner support cup, and the perimeter spot welds attaching the inner cup to the pulley.
So those features may be a good way to ID an original pulley, unless someone comes up with something different on known originals. Of course, there may be different features based on potential multiple suppliers, or changes over time.