The GMC Truck Fuel Pump, whether it sits in the gas tank or along the frame rails, is just an electric motor attached to a couple of gears that pump the fuel.
The Pickup Parts almost always give you plenty of warning.
If you do, order your Body Parts set here and be assured of quality parts that can handle corrosion, rust and usage.
So test for fuel pressure and volume, and if either is out of spec, order a new GMC Truck Fuel Pump from us right away.