Truck bed-mounted material handling machinery primarily for use in the construction materials delivery industry, namely, hydraulic extendable material conveyors, mechanical extendable material conveyors, and truck bed material lifting platforms; materials handling attachments for lift trucks, namely power-operated loading and unloading machines in the nature of load-lifting clamps, forklift forks, push pulls, rotators, pallet handlers, fork positioners, and bin dumpers, sideshifter fork posit...