There was a '71 in the Nov '09 Legendary auction (Lot 140), going for just under $3k. I haven't seen one before or since.
'68 3d in the same auction, lot 125, did not meet reserve at $2500.
1951 Topps Blueback Box, sold for $3900 in REA Spring '15 Lot 523. The only one I've seen in 20 years of tracking
