I have a 1966 Carryall. Included with it were a Motors 1969 Manual (for 63-69) and a Fix Your Chevy book. Both seem to indicate that 2 or more wires connect to one of the starter posts. I have one wire going to each post. One yellow, one black. The ammeter in the dash appears to work so it appears it's wired right. Were there just 2 wires, one for the positive and one for the negative terminal?
