A motor vehicle main chassis includes left and right main frame rails
having extending along opposite lateral sides of the chassis. An extended
rear frame member having left and right rear frame rails is disposed
below and attached to the main frame rails, the rear frame rails
extending horizontally in a plane situated below and parallel to the main
frame rails. Left and right intermediate spacer rails are attached,
respectively, to a bottom surface of the left and right main frame rails
and extend rearwardly of the main frame rails. The left and right rear
frame rails may be attached, respectively, to a bottom surface of said
left and right intermediate spacer rails and extend rearwardly therefrom.