1970 Ford Mustang Boss 429 in Grabber Blue Selling for $700,000

Whenever somebody mentions expensive vintage muscle cars, I immediately think of Mopars with the HEMI 426. However, if this Ford is any indication, prices are about to get out of control with the 1969-1970 Mustang Boss 429 as well.

It’s easy to understand why this Mustang is desirable. They didn’t make that many of them, and the gigantic engine immediately makes this a royal vintage muscle car. But $473,000 is the auction record over the past 5 years, just set at Scottsdale 2022 four months ago.

Yet one dealer, Motorcar Classics out of Farmingdale, New York is trying to shift this particular 1970 Mustang Boss 429 for $699,900. Undeniably, it’s a beauty in this color, but the price is about twice the market average.

What makes the Boss 429 so special?

It was built right at the peak of Ford’s Total Performance era for only one reason: to homologate Ford’s new hemi-head Boss 429 engine for NASCAR Grand National racing. It was a complete transformation of the Mustang, and the volume-oriented Ford actually subcontracted Kar Kraft of Brighton, Michigan to do the job.

It was a complicated transformation that required the moving of the factory-original front shock towers and a lowered front ride height. Ford also had them install several performance components, such as a Toploader 4-speed transmission, engine oil cooler, a trunk-mounted battery, 9-inch Traction-Lok rear end, powered disc brakes at the front, competition suspension with front and rear anti-roll bars, and staggered rear shocks.

In total, they made 857 (+2 Cougars) examples for the first year, but only 499 for 1970. Power output for both years was rated at 375 horsepower and 450 pound-feet of torque. Of course, like with many great engines from that era, it’s rumored that the numbers were lowered for the sake of insurance.

The racing 7.0-liter engine was based on Ford’s 385, but had a forged steel crankshaft and steel connecting rods. For 1970, they used mechanical lifters (vs the hydraulic ones in 69) and a revised exhaust system. Even though it could handle the high rpm of a track battle, the road-going 429ci V8 was limited to around 6,200rpm.

The seller of this Grabber Blue example says this car has an original numbers-matching engine, KK (Kar Kraft) numbers 2073, the earliest KK number Boss 429 to be equipped with an emissions fuel system which is pretty rare. “Coming to market after 41 years of ownership, this 429 is likely one of the most original 429’s available today and has been inspected and verified by world-renowned Boss 429 guru Ed Meyer,” they add.

I think that guru authentication is part of why this is so expensive. Boss 429 prices haven’t been this high since the 2000s boom.