By 1969, the writing was on the wall for muscle cars, and most automakers knew it. This included Ford, which was being criticized for having a performance-heavy lineup by the same publications that lauded every performance car the company churned out just a few years before. Sales of Shelby Mustangs fell so much in 1969 that the ‘69 models were kept, updated, and carried over to 1970. Yet even with all this going on, Ford was planning a potential Shelby successor.

Internally called the “Composite Mustang,” Hemmings Auto Blog reports that two concepts went so far as to be built by Kar Kraft utilizing various upscale bits from the Ford parts bin. Ultimately, the Composite Mustang never made it past the concept stage, and remains relegated to the annals of Ford history.

The Composite Mustangs left the factory as Boss 429 models before heading to Kar Kraft, Ford’s chosen supplier of concepts and specialty vehicles. From there, Kar Kraft added nicities like a Mercury Cougar dashboard, and 1969 Shelby GT500 front sheetmetal. They also closed off the hood scoops and added all white interiors to the two concepts, one in Grabber Blue and the other in Candy Apple Red.

The Composite Mustang was slated to replace both the Shelby GT500 and the Boss 429, which were in the 1970 model year and about to be de-toothed anyways. Amazingly, these two concepts escaped the crusher and wound up in private collections. When and if these Mustang concepts ever go to auction, they’ll be sure to bring a pretty penny as a “could-have-been” conversation starter.