Spending too much time on the Pre-War side and overlooked this thread - Thanks Ben for starting it.
This 'Mystery' card still amazes me. Thanks Steve for the analysis. Just amazes me that this card (I've seen about 6 total over the years) has clearer fonts on the back. Statistics and MLB logo etc. Print dot patterns on the front match 1990 Fleer Canadian - as does the 'feel' of the card. Odd.
I did send one to SGC years ago (along with a note stating my doubts). They returned it as 'Questionable'. PSA has graded at least 2 of these recently.
Thanks to everyone that has helped with this card. For more info from my website - check out:
http://www.billripken.com/mystery/mystery.html
Lots of detailed pictures etc. Long live the FF!