Integral Construction
Part of, or contained in a larger major item (a) The type of construction of private cars and other light vehicles which superseded the previous concept of a separate foundational chassis and used sheet metal pressings instead of thicker chassis members, these being integrated with the floor panels and other body pressings, or (b) The casting of crankcase, cylinder bores, or water jackets in one-piece, together with supporting webs and stiffeners for the crankshaft.
Also see: How it Works - The Car Body