I dont have any knowledge on the subject but i did a search and this site popped up with some for sale..and it appears with some differnt color jersey numbers..maybe you can contact the seller or some'n
www.vintagefootballcards.com
And this link to an article here on net54 about the subject
https://www.google.com/url?sa=t&sour...RXPftwLtO4KFgA