Abstract: Described herein are several embodiments of a vehicle chassis with frame rails having a dropped center section. According to one embodiment, a motor vehicle chassis includes a forward frame rail section and a rear frame rail section that is spaced apart from the forward frame rail section. The chassis also includes a center frame rail section that is parallel to both the forward and rear frame rail sections and extends at least partially between the forward and rear frame rail sections. A forward portion of the center frame rail section can be positioned below a rear section of the forward frame rail section to form a forward overlapping section. The forward overlapping section can define a first open space between the two sections. Similarly, a rear portion of the center frame rail section is positioned below a front section of the rear frame rail section to form a rear overlapping section. The rear overlapping section can define a second open space between the two sections.

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.