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Same hammer, more velvet – the 1966 Shelby G.T. 350 prototype

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Launched in 1965, Shelby American’s G.T. 350 worked better on the racetrack than it did on the daily commute. Once the initial thrill wore off, many buyers found the car too harsh, meaning that changes were needed to grow sales in the G.T. 350’s sophomore year. Next January, the first 1966 Shelby G.T. 350 prototype, developed to add civility without dramatically altering performance, heads across the block at Barrett-Jackson’s Scottsdale auction.

No one complained about Ford’s K-code 289, to which Shelby added an aluminum high-rise intake manifold to house the Holley 715 cfm “Le Mans” carburetor, boosting output from 271 hp to a claimed 306 hp. A high-capacity oil pan, finned for cooling, was also fitted, along with “Cobra Powered by Ford” aluminum valve covers. On the 1965 G.T. 350s, the exhaust exited through “tri-Y” headers and was piped behind and below the doors, prompting noise complaints from buyers and legal challenges from state DMVs. For 1966, the engine would carry over, but the exhaust would be sent to the rear of the car.

1966 Shelby GT350 Mustang prototype

Many buyers complained about the standard-issue Detroit Locker rear used on the 1965 cars, which created a startling “bang” when both rear wheels hooked up. Worse, differences in tire pressure or even the variable traction of wet roads occasionally led to “exciting” handling, entertaining on a racetrack, perhaps, but less so on crowded roads. In its place, Shelby substituted Ford’s No-Spin differential for 1966, with the Detroit Locker rear listed as an option on the order sheet.

To turn a profit, Shelby needed to trim production costs from the 1966 G.T. 350. Batteries remained under the hood and spare tires in the trunk, and the wood-rim steering wheel used for 1965 was eliminated, replaced by a “wood-look” wheel shared with the Mustang. The custom gauge pod that graced the dash of the first-year G.T. 350s was also scrapped, with the oil-pressure gauge making its way into the stock instrument cluster and the tachometer mounted solo, atop the dash. By the end of 1966 production, the custom lower A-arms used on earlier cars were eliminated, and the “over-rider” traction bars that required cutting of the floor pan were replaced by under-rider bars that required no such modifications. Koni shocks were replaced by less expensive Autolite adjustable shocks late in production as well, further reducing the bottom line.

1966 Shelby GT350 Mustang prototype

The car seen here was one of two 1965 Ford Mustang GT fastbacks ordered by Shelby American in May 1965 for the development of the 1966 models. Unlike the bulk of the de-contented K-code fastbacks ordered by Shelby, these were specified in GT trim, primarily to obtain the five-pod dash that would be used in 1966 models. One of the two cars was ordered with a base 289 and an automatic transmission, while the second was ordered with a high-performance 289 and a four-speed manual transmission. The automatic car, once stuffed full of Shelby-tuned 289 and fitted with a three-speed C-4 automatic transmission, was used to develop a new offering for 1966 – the clutch-less G.T. 350 – while the second car was given Shelby American Vin SFM6S001 and used to develop the manual transmission version.

Though built from a 1965 Mustang, the SFM6S001 Shelby VIN identified the car as a Shelby Ford Mustang, 1966 model, Street car (as opposed to the G.T. 350R models, which carried an R in the fifth position), first car completed. Once built to 1966 Shelby G.T. 350 specifications (then with a plain white roof instead of the Medium Blue vinyl roof), the car was photographed for company literature and used for promotional purposes.

1966 Shelby GT350 Mustang prototype

1966 Shelby G.T. 350 prototype. Photos courtesy of Barrett-Jackson Auction Co, LLC.

Shortly before its time with Shelby American was over, the car was sent to Acme Auto Headlining in Long Beach, California, for fitting of the experimental vinyl top. Carroll Shelby, it was said, hated the look, and vinyl-top cars were never offered as a factory option. In mid-May 1966, roughly one year after it was ordered from Ford, the car was delivered to California Shelby dealer Hayward Motors, where it remained as a dealer demonstrator until acquired by its first owner of record in 1968.

In 1971, SFM6S001 was acquired by Jack Schroll of Oakland, California, who retained possession of the Shelby for the next 33 years. In August 1976, at the inaugural Shelby American Automobile Club (SAAC) national convention in Oakland, California, Schroll displayed the car as a painted rolling chassis. It isn’t clear when he completed the restoration, as the car reportedly remained in storage until 1998, before being sold at a 2004 auction for $280,800.

1966 Shelby GT350 Mustang prototype

In 2012, the prototype received a comprehensive restoration, complete with a Medium Blue vinyl top, reportedly under the supervision of SAAC Judge John Brown of Piedmont, Oklahoma, a specialist on 1966 Shelby models. As a testament to the accuracy of the restoration, SFM6S001 received a Platinum Award at its first SAAC concours, and appeared at Pebble Beach in 2015, exhibited in the Shelby G.T. 350 50th Anniversary class.

The Shelby sold to the consignor last year, and Barrett-Jackson is not releasing a pre-auction estimate for the lot, which carries a reserve price.

Barrett-Jackson’s Scottsdale auction takes place from January 13-21, 2018, at Westworld of Scottsdale. For additional details, visit