Remflex 3028 Exhaust Gasket for Ford V8 Engine, (Set of 2) 1-1/4 inch width x 1-5/8 inch height Large Square Port; Ford V8 - 289-351 Windsor, Large Square Port, (Aftermarket Cylinder Heads - 2" BH Spacing), 2/Set For use with Aftermarket Cylinder Heads with 2" Bolt Hole Spacing on each port There are no rubber binders or composite materials in Remflex exhaust gaskets so they will not shrink or harden due to time or temperature eliminating the need to go back and continually retighten your flange bolts Heating and cooling of the exhaust system causes header and manifold flanges to warp resulting in gaps between the head and header which Remflex exhaust gaskets seal completely due to the thickness and compressibility of the 100 percent flexible graphite