Controls heat riser valve. Mounts on outside of exhaust manifold. Fits beside the 6 cylinder exhaust manifold. This bi-metallic spring will open and close the heat damper in the exhaust manifold depending on the engine temperature. Ready to install. NOTE: Many of these springs are lost or broken and thus the damper shaft is frozen in one position. This can usually be easily corrected. Heat the shaft where it comes out both sides of the manifold with a mild temperature torch. Slowly begin to move this shaft with a pair of Vise-grips or equivalent. Once the rust film is broken loose, it should turn easily and our spring can be attached after cooling. Graphite is a good lubricant!