You can also replace the fuel pump by lifting the pickup bed, provided it is empty. Remove (4) of the mounting bolts from the front and side mounts, Loosen the remaining (2) rear bolts till they are almost out. Disconnect the fuel filler tube shroud. Raise the pickup bed from the front (Like a dump truck) about 2ft and place a block of wood or a stand to hold it up, then replace the fuel pump. If you choose to remove the bed, don't forget to disconnect the wiring harness to the tail lamps.
On the 5.9L engine the fuel pump and automatic shut down relay are on the firewall in the engine compartment. The workshop manual says if the fuel pump needs to be replaced it requires removing the fuel tank (a 2.2 hour labor operation).