1968-72 Chevelle, El Camino, Monte Carlo, Big Block headers. Made from 304 stainless steel for maximum corrosion resistance. All tubes are CNC mandrel bent for optimal flow. These headers have 1-7/8" primaries with CNC laser cut 3/8" thick flanges. With 3-1/2" Slip-fit collectors. These headers fit perfectly. Long tube design provides awesome torque and street performance. Recommended to use a mini-starter for additional clearance. Mill finish, All TIG welded for strength and durability. These kits come with a lifetime warranty and proudly made in the USA.