A 6-2 will NOT bolt in 1 1951 A. Here's the break-down for the A series TSC Powerblocks.
6-1 will fit unstyled (with styled head and a few other mods) and styled thru s/n 583,999.
6-2 fits s/n 584,000-647,999 (pressed steel frame, 2 stick trans).
6-3 fits s/n 648,000 and up (creeper gear trans) and 60's