Where is the fuel filter located for replacement?

It is under the truck in front of the fuel tank but behind a shield that bolts between the corners of the frame. It uses quick connect fittings. Usually, you will need to use something like carburetor cleaner to spray into the fittings to flush out the dirt and rust before you use a release tool to disconnect the lines. Before removal you will need to remove the fuel pump relay (#49) in the junction box under the hood. Then try to start the engine at least twice to drain off as much of the fuel pressure as you can. Then you can change the filter.