Storage case for working machines

The storage box has at least one plate which protrudes rearwards from the vertically extending rear wall of the box and which has at least one transversely extending hole to accommodate an attachment pin (24), and at least one support element protruding from the rear wall of the container to the rear and which has an adjustable length. The plate is constructed as a rectangular or square hollow section orientate rearwards and with aligning holes in the upper and lower side sections. Independent claims are included for a ballast weight for a working vehicle with a towing device and storage box attached to it, and for a working vehicle, especially an agricultural tractor, to which is attached the proposed storage box.