The dash was taken out of the 85 C10 I bought and now I am putting it all back together. I have a part here that I cannot figure out what to do with it. It is the mint green box that has a cable that mounts to the back of the instrument cluster and screws in right beside the speedo cable. Can somebody tell me what it is and what it does? Once I screw it to the cluster, where does the other end go? Thanks for your help.