The Boss 429 was a Ford Mustang variant offered in 1969 and 1970 and is arguably one of the most rare and highly valued muscle cars to date . In total there were 1,358 Boss 429's made. The origin of the Boss 429 comes about as a result of NASCAR. Ford was seeking to develop a motor that could compete with the Hemi motor from Chrysler in NASCAR's Sprint Cup Series (then known as "Grand National Division"). NASCAR's homologation rules required that at least 500 cars be fitted with this motor and sold to the general public. After much consideration, it was decided by Ford that the Mustang would be the car that would house this new engine. The Boss 429 engine is a series 385 engine from Ford (See Ford 385 engine). The Mustang's body however was not wide enough to encompass the massive Boss 429 engine and as a result, Ford hired Kar Kraft out of Dearborn, MI to modify existing 428 Cobra Jet Mach 1 Mustangs to properly fit the new Boss 429 engine. Kar Kraft made extensive modifications to the Mustang, including widening the shock towers and extended out the inner fenders to allow this massive engine to fit. In addition, a hole was cut in the hood and a manual controlled hood scoop was added to these cars. These cars were capable of 375hp and 450ft·lb of torque. (See Boss 429 Performance Mustang Style Revised Edition by Stephen B. Strange, ISBN 0-931417-02-3)
In 1969 there were 859 Boss 429's made by Ford Motor Company. There were five different colors available in 1969 (Raven Black, Wimbledon White, Royal Maroon, Candyapple Red, and Black Jade) and the only color for the interior was black. The hood scoop was the same color as the car. All these cars were a manual transmission and there was no Air Conditioning available due to the size of the engine.
In 1970 there were 499 Boss 429's made by Ford Motor Company. There were five new exterior colors (Grabber Orange, Grabber Green, Grabber Blue, Colypso Coral, and Pastel Blue) and the interior was available in White or Black. The hood scoops for this year were all painted black regardless of the color of the car. These cars also had a manual transmission and no AC was available.
Both model years featured a toned downed approached to the exterior of the car as compared to other Mustangs of the area (see Boss 351, Boss 302, Mach 1) in that the only external identification of the car was the Boss 429 decals that were on the front fenders on each side in front of the forward tires. The rest of the car featured a very clean look that was atypical of Mustangs that Ford produced.
To show just how special these cars were, they were given special Nascar identification that was placed on the driver's side door. Each car was given a "KK" number which stood for Kar Kraft. KK #1201 was the first Boss 429 and KK #2558 was the last Boss 429 made.
Unfortunately sales started to drop off for the 1970 Boss 429 Mustangs and with higher costs, gas costs, and other internal Ford problems, it was decided that 1970 would be the last year of the Boss 429.
In present day, these cars are highly sought after and recent auctions on Ebay and at Barret-Jackson have shown some of these cars going as high as $350,000.00 or more depending on its condition and whether it has been restored or not.