Technically there is no such thing as a Mark 2 type knife made under government contract from the Korean War era. All the knives that would have been issued at that time would have been stock left over from WW2 production which was canceled in August of 1945. There are documented examples of new old stock WW2 made Mark 2s being found in Government supplies at least as late as the 1970s.
After WW2 the next contract awarded for the Mark 2 or 1219C2 pattern knife would have been 1960, but this contract wasnt awarded to Camillus. Camillus got their next contract in 1962.
This is an image of how those Camillus knives were stamped from 1962 to early 1974.
The (U.S.) stamped on the knife reflect a change to the government specification that took place after WW2 and non of the WW2 made knives from any of the four manufactures has a (U.S.) stamped on them.
In February of 1974 Camillus dropped the (N.Y.) from the stamp on the knife and they started to look this way.
This marking with at least two variations in the style of font appear from 1974 until about 1989.
Camillus sold both of these marked knives both for government contract and sold commercially.
In 1989 Camillus made their last contract knives and changed the way they were stamped again.