Casting numbers aren't the same as part numbers, so they are usually not referenced in the AIM or other manuals or catalogs.
I do recall some discussion about US-made reproductions, will have to do some digging. Think the question was raised about the cast iron quality (nodular, ductile, gray), and how you could be sure what you bought was actually US made when vendors market both imported and local, but with a significant price premium.....