The 7 Rarest Boss 429 Mustangs With Original Kar-Kraft Papers

In the late 1960s. Ford needed to get its massive 429 cubic-inch V8 into NASCAR, and the obvious choice was the Torino. Instead, they shoehorned it into a fastback Mustang, creating the legendary Boss 429. Problem was, the engine didn't fit. So Ford turned to Kar-Kraft, a Michigan specialty shop, to do the dirty work.

The Mustangs rolled off the Dearborn line without engines or transmissions, then got shipped to Brighton for surgery. Kar-Kraft chopped shock towers, redesigned the front apron, moved the battery to the trunk, and made the big-block fit. Only 1,358 Boss 429s were built from 1969 to 1970, each stamped with a unique Kar-Kraft number.

Today, even a rusted hull with a tree growing through it can fetch six figures. But the ones with original Kar-Kraft build sheets and invoices? Those can top half a million at auction.

Take KK #1238, a 1969 Candyapple Red Boss 429 that claims to be the first of its color ever made. After a rotisserie restoration in 2012 and a 2025 refresh, it's Concours-ready with just 44,057 miles. It came with two Kar-Kraft invoices, two build sheets, all original glovebox paperwork, and a history of delivery to Tasca Ford, the dealership that accidentally invented the 428 Cobra Jet.

At Mecum Indy 2025, it crossed the block at $500,500, which some say was a bargain. Then there's KK #1492, a Black Jade '69 with just 1,287 miles on the clock. Restored by marque expert Bob Perkins, it came with its original window sticker, a build sheet, and even a newspaper ad from the original family.

That one sold for $522,500 in 2023.

Not every Boss 429 hit the moon. KK #1570, a Wimbledon White '69, went for just $220,000 at Mecum Harrisburg 2022. The catch? It had a replacement engine. But it came loaded with broadcast sheets, manuals, the window sticker, and a Kar-Kraft warranty card. KK #1798, another Candyapple Red '69, sold for only $202,000 on Bring a Trailer in 2021, again with a replacement 429.

Originality matters, and with the Boss 429, it can swing the price by $300,000 or $400,000. The 1970 models are rarer, with just 499 built. KK #2100, a Grabber Blue example with a full restoration and just 427 miles since, sold for $363,000 in 2023, backed by a Marti report and Kar-Kraft warranty card.

The biggest hitter so far is KK #2275, a Grabber Green 1970 with a white interior, one of just nine like it. Unrestored with 4,899 original miles, it sold for $660,000 at Mecum Indy 2026, the highest auction price ever for a Boss 429. It came with a build sheet, Marti report, and Kar-Kraft warranty card.

The wild card is KK #2413, a 1970 competition car that raced at Sebring and Daytona. Despite build sheets, invoices, and race results, it stalled at $140,000 in 2023 and failed to sell. Collectors don't love race cars the way they love pristine originals. But sooner or later, a no-mileage, Concours-condition Boss 429 is going to rewrite the record books.