Add headrests to 67 Dart bucket Seats

Sorry, but I don't know what "have the provision for the headrests" means.
Is there a frame or something in the seat back I should look for? I'm going to
take the buckes apart before I take them over the the upholster guy to save
a few dollars. I'm "assuming" there should be some sort of frame of something
the headrest tubes could bolt too???