The tonnage rating on trucks goes back before my time, and I have been around trucks for 70 years. My father, who was born in 1901, referred to the tonnage rating already being obsolesce and meaningless when I started fooling with trucks in the 1950's. I think the Chevy in question would be considered a two ton, but other than that tonnage is meaningless. I still own a fleet of dry bulk trucks. The State of Texas still requires a tonnage rating at registration. The only number the computer will take is 5 tons and all the trucks are registered as 5 ton trucks. Empty they weigh 14,000 and the trucks are rated at 50,000 gross vehicle weight. With a load trailer, we weigh 84,000lbs with a Texas 1547 permit. We can legally transport 60,000 lbs of material. If anyone can figure out any correlation to the tonnage rating, I would like to know.