Alright so the 98 z71 I bought a couple weeks ago is in need of a fuel pump in the near future. It is right in the bottom end of the pressure range it should be and is bleeding pressure off when you turn the truck off. After all these pumps were never known for being great and this one is the original 20 year old pump so its due. My question is everyplace shows two different acdelco pumps available for this truck with the 5.7L. Without waiting for me to pull the old pump how do I know which one I need?