What are the 5 levels of organization for a truck?

What are the 5 levels of organization for a truck?
I'm guessing you're referring to the weight classifications.
Trucks are classified by gross vehicle weight rating (GVWR), which is the amount a vehicle would weigh when loaded to the maximum amount it is designed to carry (i.e., it is the sum of the weights of the truck itself, the driver and any passengers, and a full load of cargo).

There are actually eight classifications, not five. They're numbered; Class 1 is the lightest, and Class 8 is the heaviest. The classes are then grouped: "Light Duty" trucks are Class 1, 2, and 3; "Medium Duty" trucks are Class 4, 5, and 6; "Heavy Duty" trucks are Class 7 and 8.

Class 1 includes everything up to 6,000 pounds, which includes small- and mid-size pickup trucks like the Toyota Tacoma or the Chevy Colorado. Class 2 are regular full-size pickups like the Chevy Silverado, Ford F-150, and some large SUVs like the Ford Excursion. Class 3 are the "HD" pickup trucks: the Silverado HD and the Ford F-350.

Class 4 includes very heavy duty pickup trucks like the Ford F-450.

Class 5 is where you really depart from vehicles likely to be owned and driven for personal use: the Chevy Kodiak is an example.

Class 6, 7, and 8 are filled by very heavy commercial trucks: flatbed tow trucks, dump trucks, and semi tractor-trailers.
See the related link for further information.