Brian, I needed to see the back seat of a '72 because of the upholstery pattern for that year. Even then there was more than one pattern depending on options so that's why I put up the picture above.
If you go to my site and click on the "Interior" link you'll see how I made the brackets for the aftermarket seats I chose (from Summit Racing) - which had tracks or sliders built in. The mounting brackets I made allowed me to mount them in the stock location (not required), get them level since the floor isn't, and raise the seats up slightly. Most aftermarket seats have tracks built in or the tracks are available separately for specific applications. You'll see I had a bench seat originally too.