As far as I know, the major TPG grading companies very much will slab the two different (1937-D) 3 and (1936-D) 3.5 leg Buffalo nickels as those are well documented in the coin literature and many people want one, so demand is high on these. The no FG ( Frank Gasparro) initials on the Lincoln Cent came about from the same issues like the Buffalo nickels mentioned above, but the demand for the missing FG initials is rather low, so the TPG graders don't recognize those types. Something like that, and others may have other thoughts...
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