Scott:
I found the third card a few minutes ago... Please check out the scan below... According to your earlier post, the card in the middle is the blue 1936 and the card on the right is the 1937. What year is the card on the left? (It appears to be about the same color as the one in the middle...)
Is there any correlation between the location of the "PTD. IN U.S.A." stamp on the bottom and the year? Based on the ones that have been posted thus far, it seems as though the stamp is in the bottom middle for the 1936's and off-centered for the 1937.
Thanks again for your help!
