Ford began development of the "J"-Car early in 1966. It had the same basic drivetrain and suspension, but the chassis and body were a massive departure from the Mk II. Built using the latest aircraft construction techniques embodying epoxy-bonded aluminum honeycomb sandwich, it was as stiff as the Mk II, but the complete J was some 400 lbs lighter. Aerodynamically, the J-Car was a failure, and the construction left room for improvement.
After Ferrari stuck it to Ford with a 1-2-3 formation finish at the 1967 Daytona 24 Hours, Ford officials made the decision to develop the J-Car and turn it into a race winner. Having made the commitment, a team was assembled from the very best people that Shelby American and Holman-Moody employed. Only 10 days later, a prototype was in the windtunnel and the results were encouraging... very encouraging!
It looked as though Ford had a new car to go racing with. Having been advanced from experimental status, the J-Car was now designated the Mk IV. Mario Andretti and Bruce McLaren, who handled the J-Car in so many frustrating test sessions, would drive the much-refined Mk IV to Sebring for its maiden race.
