I bought an extra one of these at the Palms show because I had it under "J", not "wagon wheel" [g]. Eastman attributes this to Jack's Cartwheel in Antioch, CA from 65-72. Interesting that this chip has three painted-on red edge spots. So does the one in my collection. Black chip with Horse Head Left mold and just $20 00 with underline on the reverse. If you've never seen a silver hot stamp before, here's one.

I'll send you my spare for $15 if you need it.