Hi. I recently came across a pair of front seats out of a 1969 Mustang. They look, to me, identical to the seats in my '71 Bronco, except the mustang seats have headrests. Will these seats bolt directly into the seat mounts on the Bronco, or does it need a modification to work? The owner is trying to decide if he wants to sell them or not. They came out of his '69 Mustang.