Military vehicles are one of my hobbies (too many of those). A civilian Chevy pickup used by the military would've likely been used at a base or some other sort of post to haul people and supplies around. It would not have been a tactical vehicle and so would not have had an "official" military designation or any sort of unique equipment (unless bolted on later).

Very cool find, though. See if you can find any identifying numbers. Usually, they'd be on the side of the hood or on the front and rear bumpers. That may tell you more about where the truck came from and what it was used for.