Yamaha C1 Concert Grand ???

[Terry Beckingham]

I have a CD by Marnie Giesbrecht and Joachim Segger made on Glen Gould's 
piano that was purchased by the University of Alberta after his death. The 
piano is listed a Yamaha C1 concert grand, serial number 3020900. I can't 
seem to find anything on a concert grand with that designation. 9 footers 
are the CF series.

Has anyone heard of this model?

Thanks

Terry Beckingham