Abstract: A frameless cargo-carrying container or trailer body construction, in which at least the side walls of the container or trailer body and one or both end walls each consists essentially of a unitary aluminum alloy plate having a thickness of at least about 5/32", and preferably having a tensile yield point of at least about 25,000 p.s.i. In a preferred form of the invention at least a majority of the major structural elements of the container or trailer body are formed of suitable aluminum alloys, and in one embodiment thereof, the container or trailer body includes forged aluminum alloy corner fittings, said alloy having an average percentage elongation of at least about 15%. The overall design of containers or trailer bodies of this invention is preferably such that the inner face of each side is substantially coplanar with the plate forming that side.