Mantle and Mays Postcard Help
 

I have had this postcard for several years now and was hoping someone could help me out with a price. It has no date, but it has never been removed from the plastic. All I know is that Mickey and Willie look young. :)

I saw two completed eBay auctions stating these were produced in the 50s and 60s. Nothing definitive though. Given that they were sold at the stadium I would imagine the same card was used for many years.