In 1935, the combination of wood and metal construction was replaced by a body built solely of steel; the roof panels were welded together instead of riveted, forming a single panel. At the same time, the company debuted an early form of the school bus stop arm, though in a much different form: instead of a stop sign, the company used a clenched fist with a red-painted index finger that was propped out from the side of the bus. In 1937, Ralph Carpenter reincorporated his business as Carpenter Body Works, expanding into a larger factory in Mitchell in 1939. In 1941, the company became one of the first publicly owned bus manufacturers.