During the war years, the US was plagued with a shortage of rubber. The Japanese occupied most of the islands that grew rubber producing plants. The majority of the rubber the U.S. could obtain was sent to the war effort.
Thus, manufacturers across the country were required to eliminate rubber and find substitutes. General Motors also felt the pressures on these non-war products. One of the more notable changed items was the redesigning of accelerator pedals on their trucks. All the rubber that had provided a non slip surface was removed. As a substitute, the metal surface was given three sharp edge slots. In this way the drivers shoe sole would not slip on the pedal surface. An excellent new design. (when you have a lemon, make lemonade).