That particular shade of green is very common on older Chevrolet trucks, as from about 1941 through 1980, it was the "standard" color on them.
The rear brakes throw a wrench in the works, that would point more to it being a BM, which is the heavy duty 3/4 ton. It should also have 17" wheels. It could be possible that the engine has been changed at some point.
The hooks were most likely added aftermarket, I've never come across one with factory hooks on the bed. Same applies for the tire carrier.
