In September 1967, production was moved to the A.O. Smith Company of Ionia, Michigan, under Ford control.[3] Shelby American had substantially less involvement after this time. In February 1968, the GT500KR “King of the Road” debuted; under the hood was a 428 cubic-inch Cobra Jet V8 which was rated at 335 horsepower (250 kW).

One of the most powerful and famous Shelby Ford Mustangs of all time, the GT500 KR (which stood for “King Of The Road”) is probably one of the most desireable ’Stangs ever and definitely one of the heavyweights of the American muscle car scene.

With a massive 7L supercharged V8 engine (the GT500 KR used the new Ford Cobra Jet GT engine) generating a then powerful 248kW, the GT 500 KR embodied the essence of the American muscle car – straight-line, foot to the floor, pedal to the medal power and plenty of it. It is claimed that the 335bhp power figure quoted by Shelby was actually an understatement made to lower insurance costs and that the real power figure is closer to 450bhp – not too shabby for 1968.

The GT 500 KR has also appeared in the movie Gone In 60 Seconds, where it was modified with a new, chunkier front spoiler and nitrous oxide and was affectionately known as Eleanor.

“KR” stood for “King of the Road” – a name that was supposedly taken from General Motors. The GT-500 KR used Ford’s new Cobra Jet GT engine opposed to the 428 ci engine used in the the “67 and “68 GT500″s. The 335-hp claimed by Shelby is most likely a gross understatement. The number given by Shelby was to lower insurance costs. A total of 933 GT-500KR fastbacks were produced along with 318 convertibles.