RV8-1.1.3 Chrysler MOPAR V8 Exhaust Manifold Bolts. Thinner Wall Tubular Header Systems. These Bolts Are 3/8UNC x 1.1/4" Under The Head. 1.1/4" Bolts Are More Suited To Cast Iron Headers. Supplied With Stainless Steel Plain AND Spring Washers (As Pictured).