Boo boo in Mustang history book?

[Historybuff]

I can't remember the exact title but there is a very hefty hardcover coffee table book currently on the market by Randy Leffingwell, the hardest working photographer in the car journalist world, on MUSTANG
and it has a two page spread early on showing a fastback concept car which I recognize as the Mach I show car. But in the captions he says this car was the inspiration for the fastback 2 plus 2 Mustang (which became the fodder for the Shelby GTY350)Now when I look at that show car, it says ""67 Mustang" to me, so I think it was a later show car. I think Leffingwell heard about a fastback and assumed that, since it was candy apple red, it was the candy apple red car that inspired Ford but I say the concept that inspired Ford to build the 2 plus 2 was one built by Andy Hotten (Dearborn Steel Tubing) , a two seater coupe. I am not knocking Leffingwell's scholarship, it's just that I saw the Andy Hotten car in person in 1964 at the Greenfield Village sports car show and it was not the Mach I concept car he pictures in his book. Or am I wrong and the Mach I Concept dates back to '64? And does anyone know if the two seater coupe or Mach I show car still exist?