The 1963 421 SD Pontiac Lemans Tempest is a wild production car. It is probably the first production Muscle car if you use the definition that a Muscle car is a big engine in a non full size body. I have read that six coupes and 6 station wagons were built with alu front ends. In 1963 someone had a bright idea to run the Stock Cars against the sports cars at Daytona. The race was the 1963 Daytona Speedweek "Challenge Cup" and was an oval track race. There were Ferraris, Porsches, a Ford powered Maserati, and 427 Corvettes powered by the 427 Mystery Motor. The Stock car guys blew everyone away with a Ray Nichels prepared 1963 421 SD Pontiac Lemans. Driven by Paul Goldsmith it averaged 145 MPH to win. A J. Foyt was second in a 63 Z06 Corvette. here are some sites on Arnie "the Farmer" Beswick's drag cars. He does say that his 64 GTO was the only one to leave the factory with the alu front end.
http://www.grocerygetterwagon.com/history.htm
http://www.arniebeswick.com/photos.htm