When I started collecting vintage 20 years ago the very first card I bought was a Duffy Mayo, ungraded, excellent or better. Loved it. There was one problem. When I got home and looked in a catalog they said it was black toned and with black back and the one I had was...brown. At least the dealer admitted it was a reprint and took it back. Been wanting one since but had to be in great shape and very pricey at that. Now, a reasonable price, I just won this...if anything, it looks like a 5 and great centering. The MK they say is small pencil mark on black black and only visible at an angle....
http://www.net54baseball.com/attachm...1&d=1453038137