This is the 6V headlight out of my 51 chevy (I might have it upside down?) According to the pigtails, the polarity of the studs are as indicated on the picture. I've converted to 12V so I'm going to get new headlights but I wanted to keep the old pigtails. Someone told me that on a 12V light, the horizontal (bottom of picture) is the ground. Can someone give me the polarity for each of the studs on a 12V headlight? thanks.