PCM Exhaust Manifold Mounting Kit | Sierra 18-8503 Kit includes exhaust manifold to head gasket & mounting bolts for Pleasurecraft Marine Ford small block marine engines. PCM exhaust manifold mounting kit For Pleasurecraft Marine Ford 302 and 351 CID marine engines Used with Sierra 18-1996 manifold Includes exhaust manifold to head gasket and 8 Allen head mounting bolts Replaces Osco 28001-MK