A chassis frame including a first section and a second section. The first section includes a top plate having a first thickness, a bottom plate, and a plurality of side plates extending from the top plate to the bottom plate. The second section includes a top plate having a second thickness, a bottom plate, and a plurality of side plates extending from the top plate to the bottom plate. The first section and the second section are joined at least one transition joint. Each transition joint includes a protrusion configured to engage a pocket. Each pocket is defined by angular edges of the top and bottom plates of the first section. Each protrusion defined by angular edges of the top and bottom plates of the second section.
