Mustang Styling Prototype
I think the Mustang prototype that Birdman was referring to was probably the 1993 (instread of 1963) Mustang Mach III prototype, which sold at the Christie's Auction at Ford Design Center a few years back. It was one of two running prototypes of the new SN95 platform, and was lot more radical than the production car would turn out to be. Originally, both were red, but, somewhere along the way, this one got repainted slime green. I thought the green was ugly, but it brought some serious money.
I think I'd go along with Centerpunch - this may not look like a deal now, espescially when you can almost buy a running GT for what they're asking, but, it IS a factory styling prototype, and one of only two. There are a number of collectors and museums who like these types of vehicles. Many museums don't care if the car runs or not - they are usually on static display. I would think that someday, this non-running proto will be worth more than the average running GT. Only time will tell.
regards,
Jeff