OMC GM Small Block Exhaust Manifold | Sierra 18-1902OMC GM Small Block Exhaust Manifold Sierra 18 1902 Starboard exhaust manifold fits OMC GM 5. 0L & 5. 7L marine engines with end riser. OMC exhaust manifold Direct replacement manifold fits OMC GM V8 305 and 350 cu. in. small block engines with end riser exhaust manifold Starboard side Heavy duty cast iron Painted black Includes both gaskets and drain cap with hose clamp Manifold mounting kit P N 18 8502 sold separately Replaces OMC 912441 Replaces