Fan clutch

I am not sure if I need a fan clutch because my fan blades seem to be okay they do not spin that easy and yet not to stiff either, but I get a lot of hot air coming in from the engine. I do not know what to make of that. My temperature gauge seems to fluctuate a bit towards the over heating side, but just a bit but worries me. I just changed my water pump so I could rule that out. Second question: do parts from a Chevrolet or GM truck from later year model fit on my Chevrolet p30? I was planning on getting parts for it from the recycling yard instead of new when I could.