1970 Dart with no Headrests?

After mashing around on the seat tops, I can feel what is probably the remains or where the headrests went. I wonder if the original purchaser had it changed at purchase or the dealer changed it to make a sell.
car also has a trailer hitch and trailer brake.
I know when I was doing the oil and gas thing, we had to sleep in our Semis and years ago, did not have sleepers. If the truck had headrests that came out, they were taken out so you could lay your head back and sleep.
Maybe they got rid of them to be able to take roadside knaps.
Just seems strange they would cover them up.

Thanks for all the help FABO.