Dale, not too sure which pulley that part number relates to.
There are pulleys that have a key way and some that screw on. There are also two different diameter pulleys, large and small. The smaller diameter was so that the generator spun quicker and cut in or charged quicker, ideal for vehicles doing short stop & start trips.
The pulleys also have a different depth to them (measured from the fins to the belt(s)) groove, depending on application, for belt alignment.
They are also very thin in the casting and after 60 years, often break like that one. I have a couple of broken ones....
