Most automatic transmission vehicles close to that vintage cannot be towed 4 down. To do so you have to remove the drive shaft when towing. A real pain. Or Remco might have a lube pump for your truck. It circulates the tranny fluid while towing. They also make a driveshaft disconnect, don't know if they make one that your truck can use.
Blue Ox, Remco, and many other tow bar makers make the towing hookup easy. Again, its going to be difficult (I think) to find a baseplace for that vintage truck. But one can get one fabricated.