I would bypass the major chains and go to a quality locally owned tire shop. One that has been around for a while. Preferably one that was open when these trucks were on the road everywhere. Ask the gray haired gentleman what will work. He will know. He's been down that road.
The guys at the tire chain can tell you what their computer says will fit. whether it will or not is another story. My roommate in college put tires on at Sam's Wholesale. That scared me to death. He didn't know the first thing about tires.
