I did a search on headrests and it looks like the 68 bucket seats have the attachment points, you only need the hardware. Is this the same for 68 bench seats? I have a pair of headrests and hardware from a 70 that I can use to add headrests to the bench seat of my 68. Can somebody tell me if this can be done to my existing 68 bench seat or if I need to find a later year.