This bolt secures the exhaust manifold to the cylinder head on the host tractor. It passes through the manifold flange and threads into the head, clamping the gasket to prevent exhaust gas leakage. A loose or corroded bolt allows the gasket to blow out, creating a loud ticking sound and reducing backpressure. The bolt is manufactured to the original thread and length specifications, so it seats fully without bottoming out in the blind hole. On reinstall, clean the threads and apply anti-seize compound to prevent galling.