The 1969 Shelby GT500 carried a 428 Cobra Jet rated at 335 horsepower, a figure almost nobody believed then and nobody believes now. It was also the last Shelby Mustang Carroll Shelby had any real hand in, built during the year he walked away from the program entirely. Ford ended up re-titling hundreds of leftover cars as 1970 models under federal supervision. Read on to find out what makes this generation the one collectors argue about most.