This picture shows two trucks with Harbor Contractor /ComboMaster Bodies and Racks. Notice the Crew cab truck on the left has a Non-Forklift Loadable Style Rack extending over the length of the crew cab. The Body platform is a ComboMaster Service Body with the low rear work platform.
The standard cab truck on the right has a Forklift Loadable Rack. Notice no upper bar on the side that look like goal posts. You can see the load bar over the bed is higher than the side bar to allow the forklift forks to leave the load and exit. This Contractor body starts as a Harbor Flatbed and the Boxes and Rack is added.
In both designs, the major share of the weight of the payload is borne by the body portion of the rack between the uprights. The portion over the cab provides support and reduces deflection of long loads such as pipe and conduit.