How much is a Boss 429 Mustang worth?

The Boss 429 is the rarest and most race-engineering-intensive production Mustang from Ford's golden era. Built to homologate the 429 NASCAR engine for competition, Ford contracted Kar Kraft of Brighton, Michigan to shoehorn the enormous semi-hemispherical engine into the Mustang's engine bay — which required moving the shock towers outward. The result was a street car with genuinely race-derived architecture.

Production Scarcity

Ford built approximately 859 Boss 429s in 1969 (the "KK" Kar Kraft cars) and 499 more in 1970. Total production: roughly 1,358 cars. By comparison, the Boss 302 saw production in the thousands each year. This scarcity, combined with the 429 engine's NASCAR cachet, places the Boss 429 at the top of the classic Mustang value hierarchy — above the Boss 302 and approaching Shelby GT500 territory.

2026 Market Pricing

• Driver-quality (correct colors, running, documented): $120,000–$160,000
• Show-quality restoration: $180,000–$250,000
• Numbers-matching with Marti Report and window sticker: $250,000–$325,000+

Authentication Requirements

Marti Report authentication is non-negotiable at this price level. The door tag, fender tag, and engine block date codes must align with the Marti documentation. The Kar Kraft conversion applied its own ID plates — these should be present and intact. I'd never recommend spending north of $150,000 on a Boss 429 without an inspection from a Mustang Club of America specialist or a recognized Ford historian.

Color and Options

Raven Black, Candy Apple Red, and Grabber Orange Boss 429s are most sought-after. The close-ratio four-speed and Traction-Lok rear axle add to base value. Automatic-transmission cars exist and trade at a slight discount — the four-speed is considered correct for the car's performance mission.