I thought I would chime here.
Sorry I'm on the back end of the conversation. All the Pogs I have ever seen are like finger prints...each one is unique. For example my 68? ser # 9774 has vertical dropouts and I have never seen them on any other Pog. See attached.
http://www.wooljersey.com/
Also I have a mid seventies with internal cable routing...where that come from. If I would ever have a nick name for Sante it would be the "great experimenter"
Ciao,
Jack (Giacomo) Gabus
Laguna Beach, CA
jack@shermangabus.com