Abstract: An elongated air intake plenum is disclosed together with mounting structure for supporting the plenum at the side of a vehicle chassis such as from the frame rail of a chassis for a motor home or recreational vehicle. The plenum and mounting structure is desirably positioned rearwardly of a rear axle of the chassis.

Abstract: The vehicle frame rail in one form has front, middle and rear portions which are seamlessly joined together to form a unitary one-piece monolithic frame rail. The frame rail may be straight with an upper surface of an upper flange of the frame rail being planar. At the transition regions of this form of frame rail form, the lower flange converges toward the upper flange at a transition between the front and middle portion and diverges from the upper flange at a transition from the middle portion to the rear portion. The upper flange of the frame rail may converge toward the lower flange along a rearmost section of the frame rail.