Although described as regular die trial piece in the standard references, these year were deliberately struck for sale to collectors as part of complete aluminum sets.
Only 2 are known as follows:
1) Gschwend, V. Brand (journal #44172), A. Brand, Boyd (per 7/16/41 B.G. Johnson invoice), unknown intermediates, 1995 ANA - PCGS64
2) Newcomer, unknown intermediates, 73 FUN, Superior 10/90, Southern collection, Simpson collection - NGC67/PCGS67.
Photo courtesy of PCGS.