PS fluid is pink, easy to tell. Plus the pump itself should be wet. That being said, the hoses on the reservoir get hard and crack at the point where they are choked by the hose clamp. Look at the reservoir (should be a brown, silo-like container on the driver's side by the well, with a lid and a thumb nut holding it down), there should be two hoses coming out of it, going down. If they are wet around the hose clamp, your PS pump might yet be ok. Remove the nut, open u the reservoir, the fluid level should be up to the end of the mesh...something tells me you won't see any at all. If that's the case, go buy some ATF, fill it up and see if the noise goes away.
My winter beater 535 is leaking from the hose. I just slid the hose up higher, moved the hose clamp lower down and it still leaks but I just carry an ATF jug with me and fill it up every now and then.