"A crowning achievement in Shelby’s life is the development of the Shelby Series I, powered by an Oldsmobile V-8. This association with GM and Oldsmobile made Shelby the first person ever to be involved in the development of performance cars for all of the Big Three automakers." That would be Ford, for the AC Cobra / Cobra Mustang GT 350/500 , Chrysler for the GLH / GLHS / Viper (
http://justacarguy.blogspot.com/2006/11/goes-like-hell-shelby-glhs-cool.html#links ) , and GM for the Shelby Series 1 powered by Oldsmobile.