New Britain Wrenches
In the late 1960s New Britain changed from 8620 alloy steel to 1137 alloy steel as a cost reduction.
In the picture below the upper Blackhawk OE wrench has grooves in the shank either side of the stamping. This is the older 8620 wrench.
The lower wrench without the grooves is newer 1137 wrench. This designation worked for the New Britain / Blackhawk line. I am not aware of a similar designation for the Husky / Sparta / Penncraft line or if anything was done for the sockets but the alloy change was across the board.