The 1960s were a wild time for American automakers, especially Ford, which in many ways dominated the public relations war throughout the decade. One of the greatest racing stories of all time involves Ford’s domination of the 24 Hours of Le Mans. The Blue Ovals dethroning Ferrari after the Italian supercar build backed out of a deal with Ford is known by everyone with even a remote interest in racing. 

At the heart of the GT40 was a 427 cubic-inch Le Mans-spec racing engine, an engine that Carroll Shelby built for Ford. As it so happens, Shelby also stuck one of these GT40 engines into a GT500, creating what he called the Super Snake GT500. Only one such car was ever built, and Hemmings Auto Blog reports that it is heading to auction this spring.

The story behind this unique ride goes as such. Shelby’s chief engineer Fred Goodell was approached by Goodyear to put together a car to demonstrate the durability of Goodyear’s new “Thunderbolt” tires. Goodell rose to the challenge, dropping a 427 V8 into the a standard GT500, adding aluminum heads, an aluminum intake, a solid lifter camshaft, and a 870 cfm Holley carburetor, among other performance goodies.

The car performed and impressed, and Goodell drove it to speeds as high as 170 mph on the Goodyear Thunderbolt tires. There were reportedly plans to produce 50 Super Snake GT500s, but the car was ultimately deemed too expensive. The car was driven a bit, racking up 26,000 miles until collector Richard Ellis bought it in 2008. Now it will (probably) trade hands again at Mecum’s Indianapolis auction from May 14th to May 19th.