1967 was the first year for the GT 500 (the first GT 350's were in 1965).
The original colors of the GT500 were metallic grey with some twin black racing stripes. It featured a 1967 Mercury Cougar tail light panel minus the chrome trim, a flip-up spoiler, and two sets of air scoops on each side. This was also the first American car to feature a factory roll bar. The new GT500 featured a 428-CID (7 L) big-block V8. It was fitted with a "Hi-Po" 302, 4-speed manual transmission, and included front and rear disc brakes.
I don't know all the specs, but I did know a guy that worked at Ford in '67 and got a Shelby.
Apparently Mr.Shelby was allowed to do mods to the mustang, hence the cobra snake on the trim. Peers called it a 'Glorified Muskrat', Back in the day, nobody had respect for that little car (smaller than the rest of the Muscle Cars), therefore the Muskrat moniker.(An aside: At the Ford plant they had a Mustang Corral for the Mustang owners, very close to the entrance, and anyone that owned a foreign car had to park around the perimeter of the parking lot)
The engine was more powerful, the snake was classier than the horse, and it was a chick magnet... but now it's 40 years older.
Sorry I don't know much more about the car, but as an aging 'muscle car' devotee, I'm much more into practical vehicles... something I can tote a sheet of plywood home with.
A couple of years ago, I had a date with a guy that had a Vette. He bitched all the way that the numbers on the speedometer were too small for an old fart to read.. yet old farts were the only ones that could afford new ones.