T-4 24 Valve Stainless Diesel Exhaust ManifoldT 4 Stainless Diesel Cummins Exhaust manifold. 24v Sled Puller Stainless Diesel exhaust manifolds come with 2 ports drilled and tapped for EGT & Drive. Our Stainless Exhaust mainfolds are made with shell molding. Its a super smooth inside and out casting technology that has superior flow over and above the old type 60 grit sand paper looking and filling casting that all the other exhaust manifolds are made from. The manifolds have 3 4 inch thick