Below information provided by Bill Oliver

The cards say there are 72 in the set.  
Comparing the gallery, The Met Museum listings,
and Todd Riley's www.non-sport.com site, 
only 65 are identified.   

I tried to collect images for the contest backs.  
I couldn't find an image of the N or A. 

Since collectors would need the N three times,
my guess is the A is the short-print.