1963 Truck Identity

[tractorman4]

I recently purchased and am trying to fix up a
Chevy Truck. Problem is identifying exactly what
it is. It is flagged on the front fenders with just 20 , the title says 1 ton, and it has dual rear wheels. The rear springs are coil with short leaf overload springs. Transmission is 4-speed with granny gear. I'm needing to get some patch panels and brake parts and so forth. Can anyone identify this combination? Are the cabs, doors and fenders on the half-ton, three-quarter and ton models the same size and thus interchangeable?
Many thanks for any information anyone can offer.
sdh.