Hi Bubbas, In 1966, I purchase a set of tires and tubes from Penske Racing somewhere in Pennsylvania for my car. They were the Goodyear distributor for racing in the Northeast. They indeed had yellow caps like Dan has pictured though a little different design. Interesting that it would be 7 years before I would purchase my car. I was collecting parts that I knew I would need and could afford as a young fella. The caps were unique and asked for several hand fulls for spares. My caps have a greenish tinge almost like
zinc chromate. They are some sort of gold colored metal probably a copper bronze alloy. The style is a little different from Dan's. They have an o ring in the bottom installed probably glued as they can not be shaken out. I am going to end here and begin again. If I write too long the site drops the reply.