The Racer Walsh 2.8L aluminum intake manifold is made to work with the RWA6239 4BBL carb. You will need to use the RWA6278 thermostat housing with the new manifold. The intake manifold and carb combo are made for street driving and lower rpm off road applications, such as trail riding and playing in the mud. The installation of the manifold and carb still provide good gas mileage and an easy horsepower improvement.