The US Mark 2 Fighting Knife; commonly known as the 'KA-BAR' (although it was manufactured by several manufacturers), is arguably the most recognizable knife design to come out of the Second World War.
I will discuss the three major variations of attachment for the US Mark 2 Fighting Knife and the two maker mark locations. The first made by Camillus were produced with a heavy butt attached by a threaded nut. This design failed the torture tests and were returned to the factory (I guess some made it through as I have an example that you may view here).
Camillus redesigned the knife with the 2nd design, which utilizes a smaller butt with a keeper pin.
KABAR also produced two main types. The first had a peened butt attachment, see below and the 2nd variation used the pin type attachment, as above.
Maker marks are usually very well recognized and often deeply stamped into the blade; although it is more common to find them on the guard.
Finishes on original WWII blades varied from blue, Parkerized or plated. Handle styles also varied, however all were leather. Sheaths were originally leather until the damp conditions of the Pacific jungles began to destroy them. Plastic scabbards soon replaced them.
Information may be checked out using Coles III & IV by Cole; Military Fighting Knives by Knife World Magazine; United States Military Knives 1941 To 1991 by Silvey.