1937-D. 3 legged. MS-60 or better. A stunning, well struck specimen, rich with natural golden mint luster. A lovely coin.
The Breen Encyclopedia provides an excellent description of this error which follows:
"...the 1937-D Three Legs variety was created by excessive regrinding of the die to remove clash marks. Die clashing is a common accident in any mint. A tiny metal fragment or the like comes into the hopper among blank planchets, thence to the feeder--where it jams the mechanism and delays or prevents a planchet from reaching the dies. At which point, the dies, having no blank to stamp, strike each other instead, often repeatedly, each leaving traces of their designs on the other. Routine procedure then is to stop the press, condemn and discard the dies which have become defaced by clashing, clear out the feeder, replace the dies with new ones, and resume normal operations. At the time of the 1937 accident, the pressman (a Mr. Young), then a newcomer, was under pressure to complete a quota, so instead of replacing a pair of clashed dies he took an emery stick and ground off the clash marks, in the process removing the bison's foreleg and weakening many other details. These coins escaped into sealed sacks among normal ones, in quantity, before inspectors condemned the dies and impressions. From mint sacks the Three Legs coins reached the Federal Reserve branch banks and the general public. Strictly mint state coins (full luster on the weak areas) are very rare, though specimens in VF to AU are always available for a price".
Estimated Value $1,500-2,000.