I thought it was an AU? Could be wrong. The question is, are there others? If you know what to look for they would be easy to spot, even in lower grade. It's somethin I do if I find myself with free time at a show. I wander around looking in cases to see if I can spot a 1922 high relief. I really do think if someone went through a lot of the common circ dollars out there that sell for a little over bullion they could possibly find one.
I could be wrong too Conder - just going by memory. They had an article about it on the NGC site at one time but I didn't go look for it.
I looked in Roger Burdette's Redbook of Peace Dollars and he says it was found in 2007 and grades VF. (He also says it was offered in a Stacks sale Jan 15-16 2008 Lot 8545 where they called it a Satin Proof NCS PF60. It failed to meet the reserve. It opened at $30,000.) There is also a unique medium relief 1922 that was discovered in 2001. It was also found in a bag of circulated peace dollars, so it probably isn't high grade either.