The rear bumper guards have a single bolt mounting each to the bumper. The guard hole is located directly over the bumper mounting hole nearest to the license plate, and covers the bumper bolt.
Thanks for the kind words about my car, I think the guards work with the sharktooth grill on the front and the wider tailights (my car is a 72).
The orange Duster at the beginning of this post is a good shot of the rear of the car.
