That is the cruise control. You need to dig a little deeper into why it is not working. Take the cable loose that goes to the inside. Have someone watch the speedo and turn it a little and see if it works. If it does you know that part is good. Jack the rear off the ground and put the tranny in neutral and turn the driveshaft while someone watches the other cable that you took loose from the "box". If it turns then it is the cruise box. If not you will need to check the cables and the drive where the cable connects to the tranny.