the ground wire goes to 4 points, the battery, battery tray, the frame, and the block. All points must be clean to make a low resistance connection. A loose positive will also cause the cables to get hot due to trying to draw large amounts of current through a bad connection. The 2 wires off the positive cable supplies all the power that runs the truck - the heavy cable only goes to the starter. Also add the jumper from the last exhaust stud on the head to the firewall - it is a backup for the cab to engine and ground.