if he's doing both tanks then it might be simpler to pull the bed if he has the man power or something to pick it up with then you can just leave the tanks on the truck. there are six bolts they are not the simplest to get to and if they have never been off your in for some fun
mine had carridge bolts in them but it didnt work because the bolt would turn any way so i had to weld a nut onto the top of the bolts then just hit them with a impact gun. then unbolt the filler necks and unplug the rear lights and its should come off.