Hi Roy,
I don't know the ID on the yellow SC but they were found by the Tucson coin dealer, Ol' Jim Reynolds. He was one of the original chip dealer- collectors in the early 80's and passed away about 7-8 years ago. Jim also had the yellow MOP 10 in octagonial shape that matched the 20. Steve Passalacqua swore that it was for Steve & Cathy but none of us believed it.