Sierra 18-1927 RiserSierra high-quality 4" Riser. For use on Crusader Inboard Engines, fits GM Big Block V8 454 cu. in. Models Ch350 & 454XL; For use on Crusader Inboard Engines, fits GM Small Block V8 305-350 cu. in. Models 220 & 270; Interchangeable with: Barr; CR 20 97772; Crusader; 97772; Mallory; 9-40401; Osco; 7772; Use With: 18-0305: Exhaust Elbow Gasket; 18-0309: Exhaust Elbow Gasket; 18-1925: Manifold; 18-1926: Manifold; 18-1929: Manifold; 18-1933: Manifold; 18-8523: Exhaust Elbow Mounting Kit; 18-1918: Elbow; 18-1928: Elbow w/ 4" Outlet; 18-1934: Elbow w/ 3" Outlet;