One of the high points of the 2013 Amelia Island Concours came when Corvette Repair's Kevin Mackay unveiled the XP-819 Corvette prototype in "driveable chassis" form. The story of the car's journey from its birthplace in the Chevrolet engineering department into the hands of its current owner, Mid America Motorworks' Mike Yager, spans nearly a half-century and at times reads like a mystery novel.

In the early '60s, Chevy was still laboring under a racing ban instituted by the Automobile Manufacturers Association in 1957. The ban had been a major blow to racing diehards in the company, especially Corvette chief engineer Zora Arkus-Duntov and GM design chief Bill Mitchell. The pair knew Corvette needed a strong performance pedigree to survive.

Two groups within Chevrolet were tasked with keeping the division's performance flame alive. Duntov would lead Corvette development, while Frank Winchell would manage Chevy's overall R&D division. Both men wanted to build a mid-engine, rear-drive street car, and to that end they assembled experimental prototypes using the MR powertrain configuration.

Duntov's team completed CERVs (Chevrolet Experimental Research Vehicle) I and II and tested both extensively. Chevy R&D, meanwhile, designed Jim Hall's incredible mid-engine Chaparral 2 race car. Both teams were able to package the driver, engine, and accessories into a 90-inch-wheelbase vehicle.

During this time Winchell's team also assembled an unusual prototype called XP-819. It featured a backbone chassis with fixed bucket seats and the engine bolted to the frame behind the rear wheels. Stingray designer Larry Shinoda modified an earlier Corvair Monza GT body design he had penned so it would fit over the new chassis.

That body was filled with advanced features, including a removable roof, body-colored urethane bumpers, side door beams, and adjustable pedals. Because the engine was bolted onto the frame backwards, a reverse-rotation marine V-8 was used. A modified Pontiac Tempest two-speed automatic transmission and transaxle drove the rear wheels.

Construction was completed in 1965, at which time GM was battling lawsuits over the alleged poor handling of its rear-engine Corvair. Any mention of an unconventional powertrain layout was considered executive suicide. However, Winchell's team, with the strong support of Chevy division chief Semon "Bunkie" Knudsen, proceeded quietly with the XP-819 project.

The 2,700-pound prototype had 69 percent of its weight over the rear wheels. Not surprisingly, it was discovered during testing that rapid changes in driver input would make the car undriveable at the limit. It also radiated a tremendous amount of heat into the cockpit, making it uncomfortable to drive. But the final nail in XP-819's coffin came when engineer Paul Van Valkenburg crashed the prototype into a barrier, causing extensive damage.

Knudsen quietly ordered that the car be shipped to Smokey Yunick in Daytona Beach, Florida, who was building a rear-engine Indy car. Knudsen told Yunick to use any XP-819 parts he needed and destroy the rest. Yunick cut the chassis into three pieces and adapted the front and rear sections into his race car. The project proved unsuccessful, however, so he dismantled it and stuffed the XP-819 parts into his paint booth.

In 1977 Yunick held a "30 years of parts" sale, at which time Corvette enthusiast Steve Tate bought XP-819. Tate returned the pieces to Missouri and entrusted drag racer Delmar Hines to reassemble the car. Its first public viewing post-resto was at the 1978 Bloomington Gold Corvette show. Twelve years later, Ed McCabe bought the car at a Sotheby's Estate Auction in West Palm Beach. He lent it to the National Corvette Museum, where it was displayed for an extended period of time.

XP-819 changed hands again in August 2002, when Yager purchased it at an RM Auction. "When I bought the car, a private restoration contractor for Chevrolet contacted me and said [his company] had the engineering proposal book for the XP-819," Yager told us. "We arranged to pick up the book in Nashville, and I gave them $2,000 as a thank-you. The money was quickly returned, and I was told they did this ‘for the car, not the money.' The book included drawings, photographs, and the business [case for] this concept car."

Yager had the Mid America Motorworks team use the book to begin XP-819's restoration. They discovered that Hines had used four large rods to hold the front and rear frames together. These were removed, and the drawings were used to duplicate the original center-box section. When it became apparent that the MAM team didn't have the time to complete the work, Yager contracted noted Corvette restorer Mackay and his crew to do a full "show car" restoration.

Mackay received XP-819 in May 2011 and embarked on what would prove to be an unprecedentedly comprehensive rejuvenation project. "We have over 4,000 man hours in this car," he told us at Amelia. "It is the most extensive restoration Corvette Repair has ever done. It took a tremendous amount of fabrication, since the entire car was handmade. The body is ready for paint, and the chassis is complete, running, and driveable. We will keep the chassis like this for at least one year, so people can view the technology that was used in 1964."

Added Yager, "The doors are articulated, so they lift in the rear to clear the curb. [The car] has a clamshell hood that appeared in the 1984 C4. Some of the suspension components match those used on the Chaparral race car."

We asked Yager about his reaction to the restored chassis. "I knew I was going to be stunned because of the quality of work that is performed by Corvette Repair's crew and Mackay's commitment to detail. I am even more than blown away now that I have seen and driven it."

Following the chassis' debut at Amelia, Yager took it to several major Corvette events before putting it on display in his MY Garage in Effingham, Illinois, where it will remain for the next several months. The restored body is scheduled to be installed later this year, and, as of this writing, the completed car is tentatively scheduled to debut at the Mid America Motorworks Funfest in September.

Whether finished or in bodiless form, the XP-819 provides a rare look at the engineering process during what is considered by many to be the golden era of GM design. Don't miss your chance to view this unique piece of Corvette-development history up close.