It was 56 years ago on April 17, 1964, that the Ford Mustang debuted at the World’s Fair in Flushing Meadows, New York. It was an immediate sales success — but there were many concepts, design studies and prototypes that were considered along the way. Some of those were codenamed the “Bruce Jenner” and the “Rambo” and there was a station wagon, a four-door and two-seater body styles. Here are some images and captions from...