In addition to automobile production, Checker played a significant role as a third-party automotive supplier of OEM body stampings. In the late 1930s Checker produced truck bodies for Hudson in addition to manufacturing complete Ford truck cabs. Checker also produced truck bodies for the REO Motor Car Company. Model A (1939) The Model A was put on sale in 1940. When the Checker Model A was introduced it had more interior room than any previous model produced. It was also the first Checker to migrate away from the limousine concept with its driver dividers, focusing on the taxi commodity business: the Model A brochure, placed significant emphasis that taxi operators should consider themselves the seller of a commodity and should think of new ways to attract customers. With the Model A, Checker incorporated new features to enhance the taxi passenger riding experience, including the new landaulet top, where at a touch of a finger, the driver could lower the back section of the roof so that passengers could ride in an open-air mode. If shade was required, a cloth awning could be inserted to reduce the effects of the sun, yet still maintain the open-air feel. Passengers in the jump seats were not left out of the experience, because above their heads was a ventilated glass roof (marketed as "Air-n-Lite") that passengers could open to increase the flow of fresh air, yet still sight-see through the glass roof. Both the glass roof and the landaulet roof were Checker exclusive features, patented in 1936 and 1939 respectively. The taxi driver also rode with the comfort of Checker exclusive features. Checker claimed that the seat could be adjusted in no less than 15 positions, because the company had always maintained that a comfortable seat would allow the driver to drive longer shifts and yield greater profits for taxicab operators. This Checker exclusive had been patented in 1931. Above the driver's head was a vent in the roof to allow fresh air to flow into the driver compartment. The driver compartment was now protected during all four seasons and for the first time was heated. Gone were the days of drivers being exposed to the weather. The manual transmission shift was moved to the steering column, again in an effort to improve the overall driving experience. From the rear back, the Model A has the very tasteful streamline styling that was very popular