I could be way off, but the FOMOCO P/N (xxxx-AA) on the bag indicates it is first version, first release, at least in their records. The original was most likely superseded by more than one supplier (cost cutting push, better materials, targeting aftermarket installs, etc.) and maybe went EOL sometime back. Millions of motors use the same seal...very common I think.
Seat it flush with the outside boss where it sits. Make sure the snout isn't grooved from wear...