The aluminum heads had intakes that could swallow a tennis ball, which was great for 200-mph laps around Daytona
In 1969, Ford introduced a limited-production model to the Mustang line. This addition was the Boss 429. It was the most powerful Mustang, and the name referred to its 429-ci engine, which was built in response to Chrysler’s 426-ci Hemi and its success in NASCAR.
Named after stylist Larry Shinoda’s nickname for Ford president “Bunkie” (Boss) Knudson, the Boss 429s were built for homologation purposes to qualify the 429 engine for the NASCAR race circuit.
The Boss 429 package came with a fully race-prepared 429-ci engine putting out a conservative 375 hp, with ram air induction, an aluminum high-rise manifold, and header exhausts. It included a 4-speed as the only available transmission and a 3.91:1 “traction loc” rear axle. Also included were several other performance items such as an oil cooler, trunk-mounted battery, race suspension, and the best interior Mustang offered.
To meet homologation requirements, Ford had to offer the 429 engine as a “regular” production option and build a minimum of 500 cars for the street. Ironically, Ford offered the new engine in the Mustang, even though the Torino was used in NASCAR. Due to the sheer size of the engine, extensive modification was necessary at the front of the car, which was too narrow. So Ford contracted with Kar Kraft to build the cars.
Staring in January 1969, Super Cobra Jet Mustangs were shipped from the Dearborn plant to Kar Kraft in Brighton, Michigan, where they were converted. The Mustang Boss 429 used scores of parts only fitted to that model. On completion, each car was assigned a KK429 NASCAR production number.
Through July 1969, Kar Kraft built 858 Boss 429s. Each car cost $4,800, and the only option was a choice of color-Raven Black, Royal Maroon, Black Jade, Candy Apple Red, or Wimbledon White. Due to the cost of the conversion, Ford took a loss on each car.
With low production, big power, and a racing pedigree, the Mustang Boss 429 came at the height of the muscle car party and made its mark like no other muscle car could.