A utility truck with arched reinforcing rods incorporated into the base of a plastic truck during molding. The reinforcing rods are held in place in a mold at a predetermined distance above the mold's inner surface by spacers attached to the ends of the rods. Plastic is molded around the rods, with more plastic provided below the rods than above them, so that, when the plastic truck is removed from the mold and allowed to cool, the plastic will contract to a greater extent than the metal rods, causing the base and the reinforcing rods to bow upward, creating a convex arch in the truck's base. The arch provides an inherently strong, bridge-type structure that substantially strengthens the load-bearing capability of the truck, yet requires less reinforcing material than conventional supplemental chassis structures. In another embodiment, caster base mounts are also molded into the bottom of the truck, providing a utility truck with a unitary chassis structure.