No trying to start anything here, but do you think any of the owners of these truck stopped at 2 tons when loading? Let be serious here. Besides, am I correct to assume the "ton and a half" and "2 ton" ratings were a more a way to describe the truck's ratings.
This truck has a GCWR of 20,000 lbs. Lets say it weighs 8000 lbs empty, that would be a allowable load (by the factories standard) of 6 tons.