If it's a volt gauge, it should only need a hot wire and a ground. Can't read the markings on that box hanging on the gauge, but guessing IN would come from the ignition switch so the gauge is only active with the ignition on.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
