Mason Truck, founded by A.C. Mason in cooperation with William C. Durant, was a U.S. truck manufacturer based in Flint, Michigan. As a subsidiary of Durant Motors, Mason Truck built Road King Speed Trucks in the early 1920s.
Mason Motors was a separate venture, a Flint-based automobile engine manufacturer started in 1911, also by A.C. Mason, who first led Buick's engine works in Flint. That company was absorbed by Chevrolet in 1915, but remained under the Chevrolet umbrella until January 1, 1918, when it became known as the Motor and Axle Division of Chevrolet.