Jeff - Since quite a few good people have answered your question with a lot of detail I won't try to expand on their answers. Here are my recollections from the time (around 1964-1967). These are based on articles mostly in "Sports Car Graphic", "Road & Track" and "Car and Driver" which I scoured profusely at that time in search of anything GT40 related. First there was the Ford GT. It was not originally called a GT40 and never called a Mark I until the the time the Mark II moniker was coined. In appearance it was revolutionary with its covered rectangular headlights, rear quarter air intakes, rear facia grill opening, and a later added spoiler. There were several versions, the first having a pointed leading edge if viewed from the side and no spoiler. The radiator, or radiators, originally located in the rear body section, were soon moved to the front at which time the pointed leading edge gave way to the radiator opening surround which we now know and love and which gives the front of the GT40 its distinct look. Then there was the Mark II. It was not generally referred to in the press as a GT40 at the time, but obviously it is a GT40. There was not much discussion in the magazines as to the 427 engine as I recall, only that the Mark II was a bit faster in the straightaway. It had the large protruding air intakes located over the rear quarters, and as to the change from the twin nostrils to the larger single vent, it was not really apparent from the trackside photos that a change had been made. There were some articles which mentioned and showed photos of the early "J-Car" and the "Bread Wagon" or whatever it was called, during development, which were much different in appearance from both the GT40 MkI and MKII as well as from the later Mark IV. Then along came the "GT40 PR" and the Mark III which were accompanied by much fanfare from Ford. At the time the press said the "PR" stood for public relations. The Mark III, round headlights and all, was a significant departure in looks. The tops of the front fenders appeared to be raised to accomodate the round headlights, the side windows were different, and the tail section was elongated, auspiciously to accomodate luggage compartments. Finally, there appeared the Mark IV. It was completely different in appearance and was never referred to as a GT40 although it was also referred to as the "J-Car" even though in appearance it was significantly different from the earlier J-Car. I had saved every magazine which had any mention of the GT40 from that period. My wife threw them all out. I can't prove any of this. Just my two cents worth.
[ January 13, 2002: Message edited by: Orin Meyer ]
[ January 15, 2002: Message edited by: Orin Meyer ]
[ January 15, 2002: Message edited by: Orin Meyer ]
[ January 15, 2002: Message edited by: Orin Meyer ]
[ January 13, 2002: Message edited by: Orin Meyer ]
[ January 15, 2002: Message edited by: Orin Meyer ]
[ January 15, 2002: Message edited by: Orin Meyer ]
[ January 15, 2002: Message edited by: Orin Meyer ]