If you can smell the wood burning it's because you got me thinking...........

I believe the Fomoco is going to be your OE unit and the Motorcraft is/was a new replacement part (not rebuilt or reman) for the Ford line. The MoCraft probably addresses a concern that they might of had and changed to update. If I remember right I think there was a big difference at the time of the warranty for the part. On some Motorcraft parts Ford used to pay a bonus if they were sold as they commanded a higher price for perceived great value/service.

I know they gave a $150 pop for a MoCraft engine sale so some of the MoCraft line had spiffs available.