Hi, Jon. I would guess it's a 1.5ton. It has 10 lug wheels. One tons had 8 lugs. The fronts just left off 5 studs. It has a short wheelbase (137"?). Check the GVWR. It should be on the kick panel by driver's door & should show about 14k pounds. More than that & it's probably a 2ton.
By the way, nice truck. I wish I still had my '51 1.5ton.
Scott