This high rise intake manifold (spread bore with dual bolt pattern) is designed for all big-block Chevrolet 396/502ci engines with our current oval port aluminum heads for 1975 and earlier large oval port iron heads. This is the latest in design and technology in dual-plane manifolds. There are no provisions for a hot air choke, but it will accept a divorced choke or electric chokes on the carburetor. Technical Notes: This manifold accepts air conditioning brackets and alternator brackets. It will not fit on many Corvette models with manifold height 6" at rear and 4 1/2" in front. (Check for hood clearance first.) Use intake manifold gasket P/N 12366985. Use intake bolt kit P/N 12367959.