If you're converting your 1970 - 1972 Buick Skylark or GS to Factory Gauges you will need to make sure your wiring looks like this . . . . . The Gauge below is the reproduction made by TPP. It to will need the wiring orientation as shown. IF you have a pig tail that converts the wiring then you should be all set. But for those of you going from Warning Lights to Factory Gauges you'll want to make sure your wiring matches this.....
You can also carefully remove the pins of several of the wires from the factory harness plug and put them in the proper location for the rally gauge pod. There's a thread on which wires that need to be moved and where.