The PSA set registry has 599 cards listed in their two mega-team sets for the Yankees from 1951-1969. It looks like they're lacking multi-player cards such as League Leaders, etc. Here are links to the composition of each set:
https://www.psacard.com/psasetregist...mposition/7711
https://www.psacard.com/psasetregist...mposition/7701