Gemeinhardt hasn't been able to tell me much, aside from the fact that their best guess is its from the late sixties or early seventies. Looking around the internet, for Model C Piccolos, they all seem to have the same engravings as mine. < C > , followed by Gemeinhardt, Followed by Elkhardt, IN, then the serial number directly after.
Most of the other Gemeinhardt Piccolos have the model printed in between Elkhardt,IN and the serial number. Mine does not.
Gemeinhardts website says model C's start with 1 and 3 as the first digit serial. Mine is six, however, I did find a music shop online that is selling a spitting image of mine, advertised as a Model C, with a 6 as the first digit of the serial.
Gemeinhardt did say they lost some of their records, so maybe it is a Model C? If you go by their serial numbers for instruments they have data on, the 6 would indicate it is a 4PSH I believe, but every 4PSH has that model in between the manufacture location and serial, and does not have the < C > above the logo.
Maybe it's just a late model C Piccolo? Just speculating, but this is interesting for sure.