Did you know that GM made a 1500 HD? Yeah, me either. I guess its a 1500 chassis and body with the stronger 4L80e and the 6.0 V8 as well as stronger springs, and 8 lug hubs (and presumably the 14 bolt corporate rear end). Basically its just a 2500 without all the extra “heavy duty”ness of the exterior and a little lighter weight.
I knew that Ford did the same trick when they first introduced the Taurus F150 (10th generation) as the F250LD (Light Duty) with 7(?) lugs and stonger springs and axles as a stopgap until the new HD body styles came out. So you could either get a 3/4 ton light duty or 1/2 ton heavy duty, which just goes to show how pointless the words “duty” and “ton” are in the truck world.