The taillight and spoiler treatment are correct for the GTCS, as are the side scoops. It should have the louvered turnsignal hood with twisting lock pins, as well as the rectangular Lucas foglamps BlueStreak03 mentioned.
I think the High Country Special had the same appointments, and was only available in 3 colors, one of which was a blue. I also think the GT California Special was only available in a few colors. They were basicly coupes, with the '68 Shelby treatment, minus the extended hood and grill.
Hopefully the original door tag is still there. That will really tell the tale.
I'm certain it's not a Shelby, but nonetheless, is a great find!
__________________ 1992 Deep Emerald Green Mustang GT Hatch, 5 speed, 2.73s, Mac fenderwell cold air intake, '93 Cobra MAF, Mac 70mm throttle body & spacer, Explorer intakes, Mac unequal headers & offroad pipe, Magnaflow catback, Walbro 110lph fuel pump, Jet adjustable FPR, MSD Blaster coil, Accel 8mm wires, FRPP aluminum quadrant, UPR firewall adjuster, stock cable, Granatelli upper control arms.
Waiting to go on: Granatelli lower control arms, and GT40 Iron heads! | 
1968 Mustang Not sure what it is.. Is it a Shelby ,California Special, High Country? 
