1956 Corvette SR2

designed for Bill Mitchell, and 3 were made. The first was test and eval, the 2nd was for Bill personally and to get some racing trophys, and he had Smokey Yunick prep and maintain it. So many parts were made from lighter weight stuff, that they shaved 700 pounds off the factory model

info and images from http://www.conceptcarz.com/vehicle/z15199/Chevrolet-Corvette-SR2.aspx

1957 Corvette SS

it was built by buying a Mercedes 300sl, and recreating the chassis with a tube frrame, and mounting the Corvette racing gear to that. Magnesium body parts to get it lightweight, and they went racing at Sebring