Sub-Frame and Step Assembly for Truck

An assembly is described for connecting a step or other components to a tow truck or other commercial truck using a sub-frame. The sub-frame includes chassis connection elements that are attached to a chassis of the truck and support elements that extend perpendicularly away from the chassis toward left and right sides of the truck so that the step, a toolbox, or other components may be attached thereto. The step is installed at a height that allows access by a user standing thereon to a bed of the truck and to any items located on the truck bed. The assembly may also include a rear bracket assembly for attaching rear fenders to the truck.