I have a 2004 Ram 5.7L Hemi 4x4 that the oil pressure went to zero. Unless you are mechanically inclined, do not attempt replacing the oil pump yourself. I was a ASE certified master mechanic many years ago and it was a major deal for me, of which I have not finished yeat. I have a factory manual on this truck and the first step to replacing the oil pump is to install special tool # 8534 (of which more than likely only a deal would have) to raise the engine to remove the oil pan. Well on a 4x4 not only is the engine attached to the frame via motor mounts the front axle and housing is also attached to the motor. I won't say how I managed to subvert this problem, but it cane be done.
