The Edelbrock Performer #21944 intake manifold is designed for street 253-304-308 c.i.d. Holden V8 engines. This Performer intake manifold is a dual-plane design that is tuned for excellent throttle response from idle to 5500 rpm. The Performer Holden manifold has been designed to fit both cylinder head bolt hole patterns. Pilot holes have been drilled on each side of the exhaust crossover for early or late model cylinder heads and will need to be drilled out depending on application. Will not fit EFI Heads (see #7594). Accepts both square-bore and spread-bore carbs. Fits Red/Blue/Black engines. Does not have a provision for external heat crossover.