I have a 1986 Chevy C10. The oil pressure stays at about 60 all the time. The sender is new so I want to see if the gauge is bad. I have several stock electric gauges from the junk yard. Is it possible to hook wires to them to see if they read differently than the one in the dash? They have three pegs. My guess is they go to pos., neg., and sender. Am I on the right track?