When I swapped my car's 4 cyl for the 5.0, I added a autometer oil pressure gauge and sending unit. Now I'm pulling it out and going back to the stock gauge. I bought the oil pressure switch from Autozone but I think I'm missing something. My brother recently did the same thing... he robbed the sending unit from a bone stock motor we had laying around and it had some kind of additional voltage regulator (or something) connected to it (between the sending unit and the harness) and I'm wondering what it was and if I need it... Anyone have any insight?