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Compared to a production car, a race car’s mission is so simple. So straightforward. It is addition through subtraction. Take away everything that civilizes a car and what’s left will be quicker and faster.
Less than two years after it was introduced in April 1964, Ford had sold over one million Mustangs. Of those, only 36 (maybe 37) were Shelby GT350R models built to race. Those three dozen cars rode horribly, rattled in terrifying ways, had obnoxious and load exhaust systems, their fuel economy sucked and each cost about twice what a regular Mustang did. All the things that made the Mustang a useful daily driver was missing. What was left was awesome.
“We sometimes find it difficult to know when to take Carroll Shelby seriously,” wrote Road & Track upon encountering the GT350 (non-R) for the first time. “He’s a great kidder. He has been known to put effort into staging a really elaborate stunt than most people will to get rich. Therefore we’re never really sure whether what he does is for real or is simply a result of his far-out whimsy.”
Shelby’s Ford whimsy was triggered by the compact, lightweight and powerful “Windsor” small-block V-8 introduced for use in the new, midsize 1962 Fairlane line of two-doors, four-doors and wagons. Replacing the awkward and lazy “Y-Block” V-8, the Windsor could, Shelby was sure, slide into a feathery European sports car and produce a capable race machine. That European sports car was the AC Ace and the resulting mutant hybrid was the Shelby Cobra.
So even before there was a Mustang or a GT350 or the R, Shelby was already racing the engine used in all of them.
Therefore, in creating the GT350 during 1965, Shelby decided to leave Ford’s factory warranted, “High Performance,” 271-horsepower, 289-cubic inch Windsor V-8 pretty much alone. The significant power bump coming the addition of a 715 CFM Holley four-barrel carburetor on a cast aluminum high-rise manifold, exhaust headers, Glaspak mufflers and an oversize oil pan. Those bare, external tweaks were enough, claimed Shelby, to boost total output to 306 horsepower.
Most of the rest of the mechanical substance of the GT350 was re-purposed stuff scavenged from the Ford production parts bin. The Borg-Warner T10 four-speed manual transmission was a regular Mustang production option. The nine-inch solid rear axle was fitted with a Detroit Locker differential and used the big drum brakes off station wagon models. Up front were 9.5-inch diameter disc brakes. Koni shock absorbers were added at all four corners, a one-inch diameter anti-roll bar was fitted to the front suspension, the power steering was quickened and enhanced with a new idler arm and Pitman linkage, the suspension was lowered and stiffer springs used. The rear seat was ditched and a plastic shell filled its space while the heavy steel hood was replaced by a fiberglass replica with hood pins. And between the front shock towers was a “Monte Carlo” bar swiped from export model Mustangs that stiffened the structure up noticeably.
The GT350 wasn’t quite a racer, but it was ready to race. The R-model wasn’t a radical upgrade from the street machine, it was more like a nudge.
Like all GT350s, the R models started their lives at Ford’s assembly plant in San Jose, California – near the center of what would soon become Silicon Valley. The Mustang 2+2 fastbacks destined to become GT350Rs came out of San Jose missing their steel hoods, sound deadening, Mustang badges, side glass, undercoating, seam sealant, heater, rear glass, gas tank, door panels, headliner and anything covering the bare steel floor. They were the raw essence of Mustang; a sheetmetal box with a few of the right pieces to race.
Once transported down to Shelby’s facility in Los Angeles, the raw Mustangs had their engines pulled so they could be balanced and blueprinted for race duty. The cylinder heads were sent to Valley Head Service in Northridge for porting and polishing while the rest of the engines went into Shelby’s engine shop where they were torn down, balanced, re-assembled and broken in on an engine dyno. Like the regular GT350s, they were equipped with a high-riser aluminum intake and a Holley 715 CFM carb and breathed out through tri-Y exhaust headers. According to the Shelby American World Registry (1987 edition) R model engines produced between 325- and 360 horsepower with the rated goal being 350. In place of the production Mustang roof side vent, an aluminum panel was riveted on. Plexiglass windows were fitted to the sides and tail and both the front and rear bumpers were omitted. A new fiberglass valance replaced the front bumper and directed air for engine and brake cooling. And the fiberglass hood’s scoop was in fact functional. Because the GT350’s suspension was tuned by race driver Ken Miles to be effective on race day, there was little reason to modify it for the R-model. However, the R wore oversize Goodyear racing slicks on 7x15-inch American Racing five-spoke magnesium wheels and that meant some sheetmetal surgery was performed to accommodate them. Front fender edges were pounded flat and the rear wheel wells were radiused for clearance.
A big 34-gallon fuel tank was fabricated for use in the Rs out of two bottom halves of the stock Mustang fuel tank. These tanks were baffled to fight fuel slosh and fitted with an oversize three-inch filler cap. The battery tray was moved to the trunk for weight distribution, and an oversize Modine radiator built up from Galaxie pieces was bolted in.
And that’s about it. Whatever seats were lying around Shelby were bolted in and the cars shipped to racers around the country willing to pony up the $5995 (base price – about $57,000 in 2022 money) necessary to buy one from a Ford dealer.
The GT350R was a winner immediately. The first batch of Rs went out to established racers in the SCCA’s various regional divisions and began winning. A lot. That was apparent in the second SCCA American Road Race of Champions that November at Daytona. This invitational race was open to the top three points earners in each of the club’s six regional divisions. Five of those six divisions were won by GT350s in their first year of eligibility. So out of the 14 cars and two alternates entered in that race, 10 were GT350s. And the winner was Shelby factory driver Jerry Titus.
The last batch of GT350Rs was built during 1966 and there wasn’t a great demand for them. It was, after all, a race car not built to drive on the street. And it was expensive. But it was glorious.
Over time, most of the original GT350Rs raced to the point of mechanical exhaustion. But those that survive today, are among the most (if not the most) valuable of all Mustangs. At Mecum’s January 2022 auction in Kissimmee, Florida the first of them, the car used by Ken Miles in developing the R model, was sold for $4.07 million. That’s the highest price ever for a Mustang. Yes, it’s more than the $3.74 million for which the 1968 Mustang GT390 driven by Steve McQueen in Bullitt went for in 2020. In fact, the previous record for a Mustang was for the same GT350R in 2020 when it sold for $3.85 million.
It may have only been a nudge that turned a GT350 into a GT350R, but it was a Hell of a nudge.