As early as Shelby began offering the GT350 package, a supercharger was under development and eventually became an option. It included a Paxton/McCulloch unit that raised power to over 350 bhp.
The very first Supercharged GT350 was finished January 25, 1965 and it became the prototype for rest of the series. David Gooding & Co. sold it at their upcoming Scottsdale Auction for $380,000 USD with an estimate of $300,000 to $400,000 USD. An exerpt of the description follows:
Auction Description Excerpt.
“Advanced Prototype” 5010, only the tenth Shelby Mustang to be built, was delivered to Shelby-American on December 18, 1964, and Shelby’s extensive performance modifications were completed by January 25, 1965. Chassis 5010 was then sent to the engine department to be supercharged, thereby serving as the lone prototype test bed for the Paxton/McCullogh supercharger, which was offered as an option on later production cars. In May 1965, this Shelby was sent to Bill Stroppe to be fitted with its distinctive 1965 Thunderbird tail lamp units while still in its term of research and development service, a fact supported by the minutes of a Shelby American meeting. Throughout its time at the factory, the specially equipped prototype was used by Shelby-American for publicity and show purposes as was done with a handful of the earliest examples. It is the only 1965 GT350 prototype to be equipped with a Paxton/McCulloch supercharger – a feature later offered by Shelby-American as an option for the GT350 range.
As the tenth car off the line, 5010 pre-dated the familiar Shelby serial number sequence that began with “5S” for the 1965 street-prepared cars. The first 31 cars did not have the “S” in their Shelby-American numbers, hence this car is known as SFM5010. Also interesting to note, the earliest cars had their familiar blue rocker stripes and GT 350 lettering hand painted instead of the production pressure-sensitive decal strip. This GT 350 was also used to develop many of the modifications that were integrated into the 1966 GT350s, including the Shelby/Cragar road wheels, folding rear seat and functional brake cooling ducts.
It is widely accepted, given the physical evidence found in numerous places on the car, that 5010 was the promotional car rented to Paramount Studios for use in the James Caan Stock Car racing film Red Line 7000 in early 1965. The unique GT350 served as the daily driver for James Caan’s character and is prominently featured in a night scene where it can be seen drifting through the corners of Ascot Speedway in Los Angeles. The appearance of the GT350 in the film gained Shelby some early, well-placed exposure to many potential customers and racing fans.
The SAAC report further states that the car retains its original drivetrain and appears to be in unrestored condition with all its original and distinctive optional equipment present and intact. The provenance of the car is supported by documentation including the SAAC report compiled by 1965 Shelby Registrar Howard C. Pardee, dated January 24, 2007. Further documentation confirms that the Shelby and Ford serial numbers found on the car match those which are on file with Shelby-American. Today, this one-off GT350 shows less than 50,000 original miles and, with the exception of fresh paint, remains an exceptionally original and beautifully preserved example.