Just put in 4bbl carb and manifold also adding Mallory Unilite Ignition and a new coil. The old coil had no markings as to which was positive and which was negative. There was cap that slid off the coil that contained the wires, also with no +/- markings. How do I figure what truck wires are positive and which is negative. One has two wires that come together the other is a single wire. The one with two wires has one that runs to a dead end of some sort of cylinder.