73 Duster Cluster broke pins

My duster had no instruments in the cluster, just a big hole cut into it for the summit tach with oil, water and volt gauges built into the face of the tach. Every factory gauge a lens where missing and covered with cardboard and painted flat black. I have bought 2 clusters on ebay and both are missing the same pin to the blue/white tracer power supply. How or where do I find parts to replace or fix this problem? BTW how do you add a photo to your message? I don't know what / or where a URL is.