It is designated as a Mark 2 Knife.

K-Bar was actually just one of the makers. The others were Robeson, Pal, Camillus, later examples were made by Conetta, Utica, and again Camillus. Leather scabbards and later gray plastic scabbaeds. And you are correct about the later being post WW2 and used in Korea and Viet Nam. The easy way to know it is one of the post war is the stamping. It will be on the left side of the blade, U.S. over either Conetta, Camillus N.Y., or Utica Cut. Co.

I carried a Camillus in a plastic scabbard attached to my left shoulder my tours in Viet Nam. It was a handy utility knife.

I have seen mint examples in leather scabbards sell for $250 and up. Mint in plastic scabbards $150 and up.

Here are a couple from my collection.