Rams Horn Cast Iron Exhaust Manifold Set, SBC, 69-72 Blazer. Gaskets and hardware included. 1 3/8" primary port with a 2.5" collector. These exhaust manifolds are based on the famous high performance rams horn style from the 50's and 60's. Manufacturer from heavy cast iron without injection ports or alternator bracket provisions. Leak resistant for long lasting performance. A rigorous quality inspection has been undertaken to ensure that this part conforms to product standards.