This manifold has provision for external water bypass and features (4) corner water outlets, dual distributor hold-downs, includes a square bore carburetor adapter & gasket. Will work with a late model style water neck, alternator, HEI and air conditioning brackets. Will also fit 1996 and later Vortec engines with minor modifications. The modification is not to the manifold itself. It just requires running a short section of heater hose from the pipe tapped hole in the front of the manifold to the 5/8" hose nipple on passenger side of the water pump