7423,
From what I have found, many of the 1968 'California Special' GT/CS 289 2V and 302 4V cars did not come equipped
with the 'GT' Option Package, which also included the GT center caps for the 14" x 6" Steel Wheels.
Though they were GT/CS cars, the GT Option Package had to be ordered for the car, at an additional cost of $148
Many came though with the blank Center-Caps (as seen below) and standard 7.35 x 14" tires.