One of Ford’s most legendary muscle cars is set to cross the block at Mecum Indy 2026, as this 1969 Ford Mustang Boss 429 Fastback (Lot S131) prepares to sell on Saturday, May 16.
This isn’t just another Boss 429—it’s KK No. 1255, one of the first 50 hand-assembled examples ever built, and one of the highly sought-after early cars equipped with the 820-S engine. For collectors, that alone puts it in rare territory before even considering the level of restoration and documentation that comes with it.
Built for NASCAR, Not the Street
The Boss 429 exists for one reason: homologation. Ford needed to get its new 429 engine into NASCAR competition, and that meant building street versions—even if “street” was doing a lot of heavy lifting.
To make it happen, Ford turned to Kar Kraft, which heavily modified standard Mustang bodies to fit the massive engine. Shock towers were relocated, suspension components were reworked, and the result was a car that felt far more like a race machine than a typical production vehicle.
Officially rated at 375 horsepower, the Boss 429’s real output has long been understood to be significantly higher.
Early Build, Top-Tier Specs
This example stands out as one of the earliest cars produced, part of the first batch of 279 units fitted with the 820-S engine. That means heavy-duty internals, including NASCAR-spec connecting rods and a forged crankshaft.
Power is sent through a Toploader close-ratio 4-speed manual transmission to a 3.90 Traction-Lok rear axle, delivering the kind of mechanical, driver-focused experience that defined the era.
Additional features include power steering, power front disc brakes, and the factory performance hardware that made these cars so formidable both on the street and in competition.
Concours-Level Restoration
The car has undergone a Concours restoration by SAAC head judge Ed Meyer and Meyer’s Cars, bringing it back to an exacting standard. Details like correct paint daubs and chalk marks remain intact, reinforcing its authenticity and attention to detail.
Finished in Candy Apple Red over a Black interior, it also features the Deluxe interior decor group, color-keyed racing mirrors, and the Visibility group. It rides on Magnum 500 wheels wrapped in Goodyear Polyglas GT tires, completing the period-correct look.
Documentation includes a build sheet, owner’s manual, Marti Report, and factory correspondence.
One of the Most Important Mustangs Ever Built
With just 859 Boss 429 Mustangs produced for 1969, and only a fraction of those being early 820-S cars, examples like this rarely surface—especially with this level of provenance and restoration.
This is the kind of car that sits at the top of the Mustang hierarchy. Not just rare, but historically significant.
When it crosses the block at Mecum Indy, it won’t just be another sale—it’ll be a moment collectors pay attention to. Because cars like this don’t just represent Ford’s past. They define it.
This year marks the 39th Mecum Indy with over 3,000 vehicles for sale and many lots of collectible memorabilia. Visit the website to see fantastic vehicles- MANY AT NO RESERVE!
Shawn Henry