Boss 429 Mustang Fastback - The Ultimate Classic Sports Car

Boss 429 Mustang Fastback - The Ultimate Classic Sports Car

Last Updated February 5, 2020

Boss 429 Mustang Rear

There’s rare, and then there’s Boss 429 Mustang Fastback rare.

Rare is a word that’s thrown around often in classic sports car circles, but one of the truly limited-production sports cars out there is the legendary Boss 429 Mustang Fastback. Its impact on the history of the pony car is inversely proportional to the number of models produced. The mark it left on the automotive landscape — despite being produced in only 859 units — is impressive. In some automotive circles, it is simply referred to as the “9”.

However, the success and reputation of the 429 is no fluke. There are some very concrete reasons why we’re talking about the Boss 429 today, as it had significant performance upgrades over the standard Mustang on which it was based. It also carved out a unique position in the history books alongside two other legendary Mustangs: the Boss 302 and Boss 351 models, all designed by Larry Shinoda. Let us walk you through what is considered the ultimate iconic sports car.

Success Isn’t Always Measured in Sales

It would be easy to look at the low volume of 1969 and 1970 Ford Boss 429 Mustang Fastbacks sold and assume that it was a flop. Only 859 units?! This number seems like nothing compared to the original Mustang that sold over 1,000,000 units in its first two years. We have to dig into the reason why the 429 was conceived in order to appreciate why so few were built.

The story is similar to the 302 and 351 Boss Mustang legends. The success in racing those cars had whetted Ford’s appetite, and they wanted to build a challenger for Chrysler’s Hemi-powered racecars to compete in the NASCAR Grand National Division.

Boss 429 Mustang Interior

To discourage manufactures from building a handful of impossibly expensive racecars that had no link to the real world, NASCAR rules dictated a minimum of 500 copies must be produced and sold to the public. Thanks to this rule, Ford was forced to be creative and innovative in creating their newest and most potent Boss ever.

The end result was a racecar that followed the Boss rulebook to a "T." Throw a massive, powerful engine into a Mustang. Upgrade the transmission, brakes and suspension. Add a few discrete visual improvements. Hold the line on non-performance-related improvements that would add weight and take away from the purity of the newest Ford track car.

The car that came from this tried-and-true formula was a powerhouse. To be sure, this wasn’t a simple engine “drop-in.” The massive 429 V8 wouldn’t fit under the hood of the 1969 Mustang, so significant work had to be done. Ford engineers were already busy with several other high-performance Mustang variants, so they subcontracted a company called Kar Kraft, headquartered in Michigan, to modify the Mustangs into the 429 models. Several major changes were made once the Mustangs were shipped to Kar Kraft:

  • The strut towers and inner fenders were moved out to make room for the engine.
  • Front suspension mounts were relocated as they interfered with the block and manifolds.
  • The battery was moved from the engine compartment to the trunk for lack of space.
  • A rear sway bar was added to enhance the handling of the nose-heavy ’Stang.

These big changes resulted in a Mustang with a very different on-track feel than previous Mustang racecars.

A Handful of Other Changes

Once the Boss 429 Mustang was built, a few other changes were made to add to its appeal on the track. A 3.91 “Traction-Lock” limited-slip differential was installed in back. The 429 revved high for such a big engine, and an 8000 rpm tachometer was installed to reflect the high engine speeds. An engine oil cooler was fitted to keep the oil at the right operating temperature. The driver could even adjust the airflow via a manually controlled hoodscoop popping out of the hood.

Visual changes were limited to a unique lower chin spoiler and a few exterior decals carrying the Boss 429 name. There was no doubt about the NASCAR-inspired origins of the Boss 429 Mustang, as each and every car received special badging inside the driver’s door. This is one-way enthusiasts identify a true original Boss 429 Fastback.

Most would agree that this super Mustang was amongst the most visually understated, which is a positive aspect for fans, but a bit of a disappointment for other car enthusiasts. Any disappointment in how the car looked could be easily displaced with a drive, however.

What About Performance?

Strapped into the driver’s seat, hands on the wheel, right foot jammed to the floor, the true appeal of the Boss 429 Fastback became evident. The incredible horsepower and torque of the monster 429 created some truly impressive stats. There were Ford’s official numbers, released to keep the insurance companies at bay, including:

  • 375 horsepower (280 kW)
  • 450 ft./lb of torque (610 N-m)

But dynamometer tests at the time and since that era show the 429 created significantly more power, at least 500 hp (370 kW), if not closer to 600. In all cases, the engine is capable of significantly more power with few modifications. This is one of the advantages of a huge 7.0L displacement that was factory limited to 6,200 RPM for insurance purposes, but could be run up as high as 9,000 RPM.

Boss 429 Mustang Performance

Some experts claim that the Boss 429 could hit a blazing top speed of 175 mph when the engine was unrestricted. Obviously, it’s difficult to get anyone who owns this car to test this claim with their rare 429, but it’s not much of a stretch when you consider the Herculean stats attached to this legendary engine.

If you do own one of these very special pieces of automotive history, CJ Pony Parts is proud to be able to offer you the parts and accessories you need to keep it on the road and track. With one simple click, you’ll find yourself in Boss 429 heaven! All the parts you’re looking for are available in our online catalog. As with all of our Mustang parts, from the first 1964.5 models right up until today’s 6th generation models, we provide photos and descriptions so you’re 100% aware of what you’re buying. Some popular 1969 Boss 429 parts include:

At CJ Pony Parts, you’re bound to find the exact part you’re looking for. And these parts aren’t just reserved for original 429 owners — there are many classic Mustang fans who would love to upgrade their own car with some of the best Boss 429 performance parts available.

Pricing of the Boss 429 Mustang

Remember how rare we mentioned the 429 was? Only 859 were produced over two years, making it a sought-after sports car.

This extreme power meant that, in some cases, people would buy the car and pull the engine to use in other projects, because of the impressive horsepower and torque available. As a result, the 429 is one of the rarest muscle cars on the market today. They have been known to sell for astronomical sums at auction:

  • In 2008, two models received bids of over $375,000 dollars (at a Barrett-Jackson auction and on eBay).
  • In 2013, an unrestored 1969 sold for $417,000 dollars (at a Mecums auction).

Boss 429 Mustang Price

It’s clear that the Boss 429 Fastback has earned its place on the podium of high-buck classic cars. To ensure that these cars are around for years to come, CJ Pony Parts continually adds 429-specific parts to our catalog. They may be:

  • Mechanical components, such as suspension parts
  • Restoration parts, such as sheet metal
  • Maintenance items, such as filters, spark plugs and air cleaners.
  • Stickers, labels and 429-specific trim that give subtle clues to the cars’ origins.

In all cases, we have an easy-to-use online store, an eager and helpful staff willing to answer your questions, and a fast shipping policy that we can offer free of charge on most orders.

When you’ve invested significant money into your classic Mustang, you want high-quality replacement parts that keep your car true to its original showroom condition. We have teamed up with some of the best suppliers on the market, so we can be sure you’re getting parts that will fit properly and work as designed with your 429.

Subtle Differences

While no major changes took place over the two-year production run, there are a few differences that help Mustang enthusiasts differentiate the two models:

1969: Five colors were available (Black Jade, Candy Apple Red, Raven Black, Royal Maroon and Wimbledon White), but only one interior color (Black). The hood scoop was painted the same as the body color, and the only transmission available was a four-speed manual unit.

1970: Five new colors were available (Calypso Coral, Grabber Blue, Grabber Green, Grabber Orange and Pastel Blue), and there was a choice between an all-black or black-and-white interior. The hood scoop was now painted flat black on all models. A Hurst shifter was added to the four-speed transmission, which was the only tranny choice.

1969 vs 1970 Mustang

Many agree that the Boss 429 Fastback was one of the most understated and cleanly styled performance cars from the era, especially when compared to the other Ford Boss cars that waved their racing flag high and proud with spoilers and stripes. No matter the year, a 429 is a special machine that gets attention for all the right reasons.

More Details on the Engine

The heart of a Boss was always its powerplant, and the 429 had some seriously impressive stats. It started life as a Ford 385 engine, but it featured some significant upgrades, including:

  • 429 cubic inches of displacement (7.0 liters).
  • A unique head design that required no head gasket.
  • A hemispherical-type “crescent” combustion chamber.
  • A Holley four-barrel carburetor and aluminum intake manifold.
  • A hydraulic lifter camshaft on 1969 models and a mechanical lifter on 1970 models.

If your 429 needs an overhaul today, browse the list of parts and accessories at CJ Pony Parts. We carry major parts, minor parts and all the hardware, trim and accessories you need to maintain, restore and rebuild your ’Stang.

While you’re under the hood, take a look at the strut towers and inner fenders. These were moved outwards by Kar Kraft to make room for the colossal V8. When you consider the amount of effort and engineering that went into creating what would be the most powerful of the original Boss Mustangs, you’ll gain an even greater appreciation for it.

Racing History

If the 429 is as highly collectible as it is today, it’s because it truly did suit a NASCAR track. It chalked up many wins through the two seasons it was raced, including a 1-2 finish at the Atlanta 500 in 1969. In total, the 429 engine saw 26 wins in all of 1969. The success of the car on the track led some of the competition to complain that it was simply too competitive, and it would be pulled out of competition at the end of 1970.

This coincided with a decreasing interest in full-out performance cars such as the Boss 429 Mustang Fastback. Gas prices were climbing, emissions standards were getting tougher, and insurance companies were tightening their grip on high-performance sports cars. 1970 would be the last year for the Boss 429, bowing out of racing and production as the year reached its close.

Keeping the Legend Alive

No one knows how many 1969 and 1970 Boss 429 Mustangs exist today, but it’s safe to say that it’s significantly fewer than the original 859 copies. The incredible prices paid for the few that pass the auction block prove there is still an enormous amount of love for the Boss — and that love isn’t likely to die away anytime soon.

We hope that a few of you reading this are proud owners of a true, original 429. Even if you’re not, it’s exciting to know there’s a large and passionate group of classic Mustang enthusiasts out there who will keep this car at the forefront of pony car classics for years to come.

Let CJ Pony Parts be your partner. Browse all the 429 parts and accessories available to you in our catalog. Why not build your own “custom” Boss 429 with some of our impressive performance parts and pay homage to the original? The first step involves simply creating an account on our website.

Once you’re done, you can instantly start your shopping! Enjoy color photos, detailed descriptions and clear pricing on all parts. We want nothing to stand between you and your Boss 429 Mustang project.

To make sure you’re updated on everything new going on at CJ Pony Parts, don’t forget to sign up for our email newsletter . Simply submit your email address, and you’ll be updated regularly on new products and events. Sign up today!

Boss 429 Brochure

Boss 429 Brochure
Boss 429 Brochure
Boss 429 Brochure
Boss 429 Brochure
Boss 429 Mustang Fastback - The Ultimate Classic Sports Car

Simply referred to as the "9", the Boss 429 Mustang left its mark on the automotive landscape. Come take a walk back in time as CJ's takes a look at this legendary car's history and how it earned its status as one of the ultimate classic sports cars in history.

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