Beneath FEJ-12127-A2 is H 721. Is H 721 a date code? If so, does that translate to Month, Year, and Day (August, 57, 21)?  The date is not particularly important to me, but it might be to others. I do know it is a tach-drive distributor/w both vacuum and centrifugal advance and is correct for 1957 Tbird.