1999-02 Chevy, GMC 4.8L, 5.3L (4WD only) Truck headers. Made from 304 stainless steel, for maximum corrosion resistance. All tubes are CNC mandrel bent for optimal flow. 3/8″ CNC laser cut flanges. These headers come with air tube fitting on primary and 1-3/4″ primaries that flow into a 2-1/2″ slip-fit collectors with O2 bungs welded into the collector that flow into 2-1/2″ Off-road leads into y-pipe with donut gasket included that connects to Factory connection point with flange. Kit includes High temp RTV silicone, 8mm Header Bolt Kit, All the accuseal clamps needed also the bolt kit to connect the 2 flanges for factory connection. Mill finish, All TIG welded for strength and durability. These kits come with a lifetime warranty and proudly made in the USA.