I'm trying to convert my 67's idiot light cluster to a guage cluster without buying a new wiring harness. The tempature guage was easy to figure out how to modify wiring and change the sending unit. It's the voltmeter guage I can't figure out. I have several different wiring diagrams for a 67 but none show the factory guage cluster wiring. My best guess is to use the original same 2 wires that connected to the light across the guage. I know this would peg the guage when cranking and doesn't sound right. Can someone help me on this?