Edelbrock part #7581 RPM Air-Gap 351W intake manifold is designed for street and high performance 351-427 c.i.d. 351W Ford V8 applications. The RPM Air-Gap incorporates the same race-winning design that's been used on our Victor Series competition intakes for decades. The Air-Gap design features an open air space that separates the runners from the hot engine oil resulting in a cooler, denser charge for more power. Larger cross sectional area and a taller carb flange than #7181 for compatibility with large displacement, stroker 351W based engines. Includes bosses for nitrous and rear water crossover. Edelbrock carbs will work with Ford automatic overdrive trans (AOD) when used with Lokar bracket SRK-4000, for more info call (865) 966-2269 or go to www.lokar.com.