“Seven liters! Four hundred and twenty-eight cubic inches in a Mustang! We were expecting a cataclysm on wheels, the automotive equivalent of the end of the earth. We were pleasantly surprised to discover that the GT 500 isn’t anything like that”. Car and Driver, February 1967.
Ford’s redesign of the Mustang in 1967 increased the size and shape of the pony car. The car now featured fastback styling with a longer hood and wider body. Shelby’s transformation to a GT500 added a 3-inch longer fiberglass hood with a large hood air scoop, competition-type rear spoiler, and rear brake air scoops. The GT500 could also be identified by its quad headlights with high beams in the grille, rear quarter air extractors, and full-width taillamps.
This redesign also gave Shelby the opportunity to shoehorn big block power under the hood. The GT500 featured an OHV 428 cubic-inch Cobra V8 rated at a conservative 355 horsepower and 420 lb.-ft. of torque. The engine featured aluminum rocker arm covers and air breather, dual 600-cfm four-barrel Holley carburetors, and a cast-aluminum intake manifold. Buyers could choose between a fully-synchronized four-speed manual or three-speed Cruise-O-Matic automatic transmission.
Just how fast was the GT500? Car and Driver flogged the GT500 equipped with the three-speed automatic and walked away with a 0 to 60 time of 6.5 seconds. They also found the GT500 to be capable of running the quarter mile in 15 seconds at 95 mph.
Car and Driver gave the GT500 high marks in handling and steering. Acceleration also received high praise. Per the article, “the GT500 accelerates powerfully at any legal speed, gets off the mark with little wheelspin despite the absence of a limited-slip, and shifts very crisply”.
Great things were in store for the GT500 for the 1968 model year. First off, a new convertible joined the coupe on the sales floor. This new convertible was easily identified by its integral safety bar, which rises high and even with the top of the windshield. The GT00 received several new styling cues including rectangular foglamps mounted in the grille opening, new twin hood scoops, and new hood louvers. Cobra emblems were also added to the front fenders and passenger side dashboard.
Production of the GT500 moved from Shelby’s San Jose, California facility to the A. O. Smith Company in Livonia, Michigan. This move helped Ford gain more control of the finished product. And since there never was a formal name for the car, Ford officially named the car the Shelby Mustang Cobra GT500.
More great news for 1968 was the midyear introduction of the GT500KR. The “King of the Road” was equipped with Ford’s new 428 Cobra Jet engine that was made available late in the model year. This new engine featured a 10.6:1 compression ratio, hydraulic valve lifters, and a high capacity fuel pump. The engine also featured a ram air system with a stamped steel air cleaner and snorkel. The KR’s Cobra Jet engine was advertised with a rating of 335 horsepower and 440 lb.-ft. of torque. However, insiders will tell you this figure is actually closer to 400 horsepower. The GT500KR was still a formidable performer on the track with a 0 to 60 time of 6.5 seconds and a quarter mile time of 14.58 seconds at 97.71 mph. Approximately 1,200 KRs were built before Ford dethroned the king and discontinued the KR altogether.
1969 saw the GT500 increase in size once again. It was four inches longer and almost half an inch wider. It also tipped the scales a little heavier this year with an average weight of 3,700 pounds. Another big change this year was the GT500’s styling. It was considerably different from the Mustang from which it was based. The front featured a large, rectangular grille with two 7-inch headlamps. The hood featured five NACA air ducts. Two facing forward to allow fresh air into the engine compartment, two at the rear to remove it, and one in the middle to feed air into the engine’s ram air system. The front fenders and rear quarters also had functional scoops that fed fresh air to cool the brakes.
This growth spurt didn’t hurt performance of the GT500. The GT500 428 Cobra Jet was still laughably rated at 335 horsepower and 440 lb.-ft. of torque. It could go from 0 to 60 in 6.0 seconds and run the quarter mile in 14 seconds at 102 mph.
Ford also dropped the Cobra name and the powerhouse was now denoted as the Shelby GT500.
Shelby’s involvement was minimal this year due to a spat between himself and Ford. Midway through the year, Shelby severed ties with the automaker. Shelby’s role was not as pivotal as it used to be and he grew tired of the drama and politics coming from the Ford camp.
An unfortunate consequence of the 1969 model year was that several hundred Shelby GT500s went unsold. This predicament put Ford in a difficult position. Faced with selling these cars on the cheap or at a loss, Ford decided to carry these over as 1970 models. As easy as that sounds, it involved quite a bit of finagling on Ford’s part. One issue that needed to be addressed was VIN numbers. These cars already had 1969 VIN plates attached on a tag below the windshield, on the driver’s door, and both front fenders. Under the watchful eye of the FBI, Ford was allowed to remove the VIN plates from underneath the windshield and the driver’s door. Since the plates attached to the fenders were unseen unless the fenders were removed, these were allowed to remain.
The only changes cosmetically between the 1969 and 1970 GT500 are two hood stripes between the front and rear vents and a Boss 302 chin spoiler. A few changes were also made to help the GT500 be emissions compliant for the 1970 model year. Other than that, there’s little differentiation between the two model years.
It’s been said that all good things come to an end. The GT500 had a good run while it lasted. Even if the man in overalls and the guys in suits could get along and continue their business relationship, the writing was on the wall for the GT500. Skyrocketing insurance rates and government regulations on emissions were slowly killing the muscle car. With that in mind, the GT500 went out with a bang instead of a whimper. Isn’t that the way it should be?