Dale Amy
August 1, 2013

This is no show car. No sir, it comes across more as a history lesson—a trip back in time to days when the separation between showroom-stock and racetrack-ready was measured in engineering ingenuity rather than sponsor generosity. What we have here is an honest-to-goodness '66 Mustang FIA Group II sedan, one of a handful put together by Shelby American at the specific request of Ford Motor Company to compete in the SCCA's then-new A/Sedan class. And this example is among the most successful of the breed.

Why was Ford so interested in A/Sedan? Well, sedan racing was new to the Sports Car Club of America for 1966 and the sanctioning body's plan was to run two concurrent series, one for amateurs and the other for professionals. The professional series would be called the Trans-American Sedan Championship, which, to attract maximum OEM interest, offered a manufacturer's trophy. And Ford wanted to polish the Mustang's performance halo by winning that championship in what was the genesis of the famed Trans-Am series.

Why go to the expense and trouble of building yet another race-variant Mustang when Shelby American already had the successful G.T. 350-R? Two reasons: First, the A/Sedan rules specifically called for four seats, thereby disallowing Shelby's G.T. 350, which had been homologated as a two-seater. Second, and more important, was that Ford wanted that manufacturer's trophy all for itself. So despite being crafted by Chuck Cantwell and crew in the very same facility that produced the R-model G.T. 350, these Group II Mustangs wore Ford—not Shelby—serial numbers.

Still, there was no reason to reinvent the wheel. Clearly, Shelby American had already engineered a winning formula with its R-model G.T. 350, so that mechanical blueprint was mostly followed during the early 1966 preparation of the 16 Group II (plus four less muscular Group I) "sedans." They started life as San Jose–built, Wimbledon White, 289 Hi-Po, four-speed hardtops with 3.89 gears and Detroit Locker differentials. Ordered with disc brakes, adjustable shocks, heavy-duty front springs, an export brace, and GT-style fog lamps, the soon-to-be-racers were delivered to Shelby American on 15x6 steel wheels without wheel covers and minus front anti-roll bars, outside mirrors, heaters, or seat belts.

When this small but athletic group of Group II notchbacks rolled out the Shelby exit doors, they were essentially mechanical clones of the '65 R-model, at least in terms of powertrain and suspension. Among other details, this meant that each K-code 289 had been balanced and blueprinted, had its cylinder heads massaged, mixed air and fuel through a 715-cfm Holley on an aluminum Cobra intake, and exhaled via Tri-Y headers feeding 21⁄2-inch exhausts. Horsepower? Depends on who you ask.

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An up-sized radiator and an oil cooler were fitted, and the hopped-up Hi-Po was fueled from an in-trunk, 32-gallon R-model tank with pop-open filler and spun-aluminum splash collar. Up front, the Group II chassis received the familiar revised A-arm inboard mounting points, 1-inch anti-roll bar, specific pitman and idler arms, and Monte Carlo brace, while the rear suspension benefitted from over-ride traction bars—again, all from the R-model playbook.

The A/Sedan interiors, however, were a departure from R-model practice, as they were mandated to retain just about all factory upholstery and window glass. A roll cage was installed, along with a G.T. 350-style wood-rimmed steering wheel and a sextet of "CS" gauges. Exterior sheetmetal, including a non-scoop steel hood, had to be stock, though allowances were made for modification of the front valance to feed the oil cooler and around the wheel lips to clear the race rubber mounted on American Racing 15x7 magnesium race rims.