This EST (Extreme-Sealing-Technology) gasket set is complete with all gaskets; seals and o-rings that are used on this model; including primary gaskets. It''s the easy way to do a complete overhaul and have all gaskets that are necessary in one package to reassemble the engine. This EST gasket set contains MLS (Multi-Layer-Steel) .040" thick head gaskets which eliminates the use of dowel pin o-rings. Base gaskets are SLS (Single-Layer-Steel) .020" thick. They have .005" of high temperature Viton rubber on both sides and are the strongest on the market. Rocker cover gaskets are also .020" thick SLS. They will not weep; extrude; tear or become brittle over time. Exhaust gaskets will not hinder exhaust gas flow and will not fray into the exhaust port. Valve seals utilize Viton rubber and outer springs for a perfect seal. With 99-10 style breather gaskets