My understanding is that the part with the casting number in the neck is a service replacement. The one on the flange is the production line part. I have read this somewhere but what I read could had been incorrect. Maybe someone else will chime in.
Here are some pics I have found for comparison. Notice that the location of the casting # is in a slightly different location and the service replacement looks too crisp compared to the others..
Casting on the base on top and service replacement bottom.
Guessing that this is another service replacement. Also notice the little bump in the casting of the neck portion versus the orange painted one below
Guessing that is one is a production outlet. No casting bump on neck above #.I could be completely wrong on this but I am hoping others will chime in with what is on their original cars..