On my green '67 Z, I found the Fisher seat tag like the one posted above and the body number was for another car. Greg's explanation makes a lot of sense. My car was supposed to have headrest buckets but they didn't get installed. The car came with the headrests but no slot in the buckets to install them. The car is very close to the end of production (less than 60 cars from the end) so maybe they were just using up what was left.
The sales invoice shows a credit for the headrests although the window sticker and cowl tag show the headrests. In the same car, I found a big sheet under the front carpet called a Uniform Option Identification Tag. It basically deciphered all the codes on the cowl tag including the ones to show the Z28 option and the headrest seats. I have heard of these UOITs being above the headliners and even sandwiched between the metal in the roof sail panel area. These must have been Fisher Body sheets and could be literally anywhere in the car from the firewall on back.
-Jon
1967 Z28 street car
1967 Z28 Trans-Am race car
1967 Z28 Registry