Stop in for a cup of coffee

Did it already have headrests? Trying to remember how they go together. Some kind of plastic inset with a metal clip... Just cut an x, not a hole.
I got the headrests with the car when I bought it but they were never mounted in the seats. I also got all the hardware, etc.. I dont know if there is a place in the seats for them, thats why I kind of want to remove the covers first to see.. I would hate to cut them and they dont work. I assume all cars came with them, at least what I've seen in pictures of 71 bench seats.