The M-819 Truck, Tractor, 6x6 Wrecker, 5 ton is part of the G-908 (or M-809) series of 5 ton 6x6 trucks. Details of the history, model numbers, and configurations of the M809-series of trucks are on the linked page.
The M819 was used for wrecker, hauling, and salvage operations. Its Austin Western hydraulically-powered, engine-driven crane is used for lifting materials and freeing mired vehicles. The crane can extend from 11 1/2 to 26 feet (3.51-7.93m) and is capable of lifting up to 20,000 lbs (9,072 kg). A hydraulically-powered swing motor allows the crane to rotate left or right a full 360 degrees.
The M-819 is also equipped with a fifth wheel at the rear for hauling military semitrailers and a front winch for self-recovery. The hydraulic system operates from a PTO on the truck engine.
The M819 Truck, Tractor, 6x6 Wrecker, 5 ton, w/winch was identified with NSN 2320-00-050-9004. Manuals for this equipment will be in the TM 9-2320-260-xx series, where the xx represents the maintenance level.