Edelbrock part #75163 RPM Air-Gap intake manifold is designed for 262-400 c.i.d. Chevy V8's with 1996 and later Vortec (L31) cast iron or Edelbrock E-Tec aluminum heads. An external water bypass boss is machined into the front of the water crossover for use on 1996 and later Vortec production engines.
eBay