Abstract: A conversion structure for converting a gondola railcar or similar apparatus for transporting materials to transport cargo in the form of discrete plates or in the form of discrete cylindrical units, such as coils of steel. The apparatus disclosed comprises two longitudinally extending rails connected by a series of cross members. At either longitudinal end of the rails, the cross members are replaced by bulkheads which prevent the discrete cargo from sliding beyond the end of the rails. Preferably, the conversion structure is removable in order to permit the gondola car to be reconverted for hauling bulk cargo. In a preferred embodiment, stacking projections are provided on the conversion structure so that when they are removed, they may be stacked atop one another for storage. Improved methods of alternately transporting bulk, plate and cylindrical cargo are also disclosed.