I am installing electronic ignition on 1971 340 Challenger. I have a new YEAR 1 electronic ignition engine harness. This harness has a 5 pin connector with 5 wires in it. I pickup an ignition module at the local Auto Value. It only has 4 of the 5 pin locations populated. I see in the Classic Industries catalog they sell both 4 pin and 5 pin modules. Do I need to order a 5 pin module for this to work?