It actually could ba a homemade pos. Many of the trucks of this era were sold without beds, so the customer could put one on that better suited his needs. Anyway, sounds like a real cool truck.
Start by getting a restoration kit from Chevy. I got mine in about a week. My kit had a sketch of all the models, some of them were simply just a chassis and the front sheet metal as other bodies were mated to them to turn them into ambulances, armored vehicles, and other speacialized vehicles.