My 68 Road Runner has factory headrest. It is stamped on my broadcast sheet 5 times. They definitely didn't want to forget them.

68 Roadrunner 383 4-speed
66 Charger tubbed,caged,4 link(my first car)
68 Barracuda 318 4-speed a/c
66 Satellite 426 Hemi
70 W100 short bed 340 T/A