i am In the process of installing the interior in my 69 mustang. I have a non folding rear seat. I understand that the hinged mounts bolt to the floor fixtures. But I am confused on how the back attaches to the fixtures on the inner wheel housings. The holes on the seat back that align with the wheel housing fixtures are about 1/2 inch in diameter with no apparent way to attach. Is ther special hardware that I am missing.