The ChipGuide has them listed as UFC.

But I notice that the Staeffler guide associates them with the S. S. Rex.

Eastman (1998) does not list them in his California guide, but Armin associates them with the S. S. Rex in his California chip guide beginning around 2004.

I agree with Doug, that they could have been used at several different places. The CCC inlaid chips seem to show up rather often. Not as often as the most common generic die-cut designs, but far more often than most custom die-cut inlaid chips.

I suppose I should move the CCC chips to the S. S. Rex listing, and I will do that tomorrow. Does anyone have any opinions on that?