Power Steering pump or just pulley?
 

I have a 1999 3.0L V6 with 184,000 miles that squeaks when the engine is running. I have located the source of the squeaking to be the power steering pump. I have already replaced the fan belt and a/c compressor as well. Am I able to get away with just replacing the pulley or should I replace the whole assembly? Nothing is leaking out of the power steering pump and my power steering feels great. What are your thoughts?

When replacing the serpentine belt, did you clean the pulleys before putting the new one on? i.e.. wire brush grooved pulleys, scratch pad or sand paper smooth pulleys, BrakeKleen works wonders as well. make sure the pulleys are completely dry before installing new belt. When the belt was off, did you check each pulley by hand for obvious bearing wear? Most common cause of belt squeak is when the belt rubs the lip edge of the grooved pulley. Roughing them with sandpaper helps. Also check your pulley alignment. The belt should track true and not appear like it's angled on to a pulley. Also, never use any solvents or "belt dressings" on a serpentine belt itself.
The pulley on the power steering pump is pressed on. If the pump isn't leaking, whining or rattling, I doubt it is the problem other than a dirty pulley.