In 1941 Corbitt Company (Henderson, NC) began production of the Model 50SD6 6 ton 6x6 cargo truck for the U.S. Army. The vehicle was intended as an artillery prime mover so was equipped with a 25,000 lb. winch behind the cab and pintle hooks both front and rear.
White produced a nearly identical artillery prime mover as Model 666. Brockway produced a chassis using the same design, as a platform for Quickway revolving cranes (Brockway Model C-666/F-666, Ordnance G547) and for bridge erectors (Brockway B-666). Other models based on the 50SD6/666 design included gas tank trucks, Signal Corps vans, and tractors that were produced by Brockway, Ward LaFrance and FWD between 1942 and 1945.
The common engine for all these trucks was the 855 cu. in. Hercules HXD 6 cyl. (gasoline) rated at 202 hp @ 2150 rpm, 642 lb-ft torque at 900 rpm. The manual transmission has four forward speeds plus a two speed transfer case. The cargo truck length was 286-289 inches.