The engine is a tweaked Mustang K-code 289ci 4-barrel V8. This Shelby version put out 306 horsepower over the 271 horsepower Mustang version. Shelby engine modifications included: 715 cfm Holley carburetor, Cobra aluminum high-rise intake manifold, Cobra finned aluminum valve covers with matching oil pan, Tri-Y exhaust headers, and low-restriction mufflers. The Shelby special Vehicle Identification Number VIN is located on a aluminum plate riveted over the original Mustang VIN number. See it over the driver's side fender?