Dean Jeffries built his Mantaray to compete for the Tournament of Fame grand prize to be awarded at the Oakland Roaster Show in 1964. After working on the first Cobra for Carroll Shelby in 1962, Jeffries started work on his Mantaray project. Using parts of the chassis from a prewar Maserati Grand Prix car that he had acquired from his father-in-law, Jeffries used 86 individual pieces of sheet aluminum to form the Mantaray's body, carefully welding the panels over a complicated arrangement of steel tubes. The single seater was finished with a Plexiglas bubbletop that Jeffries made by using a tube to blow air into molten plastic until it bubbled to the size he needed. The engine he selected was a Ford V-8 with Cobra valve covers mated to a 4-speed transmission. The finished car was taken to the Oakland show on February 14, 1964 and Jeffries was awarded the first-place prize of $10,000 and a trip to Europe.