Gregory Peck's half brother raced Mustangs in SCCA, this one was a K code Shelby test mule, it was upgraded with Shelby GT 350 speed parts, then tested, then sold as is

Carroll Shelby ordered Chuck Cantwell and Jerry Schwartz to test by November and Cantwell bought a blue 271HP K-code notchback from the Ford dealer.

It was stripped and built up again with competition parts from Shelby. Modified to Group 2 specs.

When they were finished with more suspension testing, the car was sold "as is" to Donald Peck in May of 66 as a used race car.

http://www.ponysite.de/66_shelbygroup2_0.htm