I'd vote for the '68s as being the most difficult, but that's probably because I have only one. Sniff.The Mantle is interesting when you compare the '67s and the '68s. In the '67 set, Mantle's position is listed as OF. In the '68 set, with the same pose, Mantle's position is listed as 1B.Here's the '67s from one of the sheets shown above once they got graded--in mini size for Peter C....