I have an old pilots survival knife, supposedly carried by my uncle in Vietnam. Blade is 5" stamped CAMILLUS NY on the blade. I've searched and read that they were switched from 6" to 5" blades, and in the early 70s the stampings were moved to the butt of the knife. There are no markings on the butt, only on the blade. Any help identifying or more info would be appreciated. I found out at my uncle's funeral that he was part of a communications division and served 2 tours in Vietnam, and some of the missions he carried out are still classified to this day.