The picture above shows the production Mustang in its package, with the prototype being below it. There are a couple of differences you can see on the prototype. The first one is the interior is red, where as the production '67 has black interior. Lastly, on the rear quarter panel the word "Club" is in white on the production Mustang while on the prototype it's in black. It's hard to really tell it in the picture above but you can for sure see it in the picture below. There is one other difference that the pictures don't really show and that's a small color difference. The packaged Mustang seems to be more of a bluish color, while the prototype has a purple look to it. Like I said, it's hard to really notice but the difference is for sure there.
Above, is a cropped, highly detailed, picture of the prototype. It clearly shows the word "Club" in black. Very unique way to tell the prototype from the actual packaged Mustang.
The picture above shows something very unique and something that shows just how legit this prototype is. On the card art, the Mustang has red interior and the word "Club" is in black. Very unique and something worth mentioning!
While I am discussing prototypes, I want to take a minute to go over about what is appearing on eBay. These unriveted, unspuns cars are being listed on eBay and are being listed as prototypes. I'm here to tell you, those are fake and very misleading. If your looking at bidding on any kind of Hot Wheels listed as a prototype on eBay, do your homework and research. Ask other well known collectors from the hobby about them. You will soon find out if the prototype your looking at is legit or a fake.
Thanks for taking a look at this article. Hopefully it help clears up some of the misleading information that has taken the hobby by surprise.