Ted - I have made so many of these diode voltage drop leads for club members I could not count them. Weather you put the diodes on the red positive lead or the black negative lead does not matter. Just remember the side of the diode that has the little bar on it is the voltage out and the other side of the diode is the voltage in lead. So if you install the diodes on the positive lead the bar code end goes toward the ignition. If you install the diodes on the negative black lead the bar goes towards the battery. Good Luck.