I just purchased a 1970 mobile home that has aluminum wiring in it. When I saw that none of the outlets or switches were rated for aluminum wiring I went out and bought those that were rated for aluminum wiring. Looking at each of the terminations I see that somebody did a very good job of pigtailing a piece of copper wire to the aluminum wire and then attaching the copper wire to the outlet or switch. All wire nuts have the black grease in them and all the connections seem to be very sound, that is, well twisted and wire nuts completely covering the connections and screws are tight. My question is should I replace these outlets with the aluminum rated outlets that I just purchased or should I leave what looks to be a safe termination as it is? And if I should switch it out do I need to get a piece of aluminum wire to pigtail or do I just attach the two wires straight to the outlet or switch? I hope I've been clear and asking my question.