Truck box construction

A welded wall assembly construction for a truck or trailer box comprising a pair of metal panels having opposite side surfaces and end edges, and a tubular support stake between the adjacent ends of said panels and joining said panels in end to end relationship, and said ends of said panels being contiguous to and welded to opposite sides of said support stake whereby surfaces of said support stake form a portion of the wall assembly on both sides of said wall assembly between the ends of said panels, said support stake having a pair of generally planar side surfaces forming a lateral width of the stake in direction of the thickness of said panels, and wherein said panels are formed to be concave to provide increased rigidity in longitudinal direction, the amount of concavity of said panels being not substantially greater than the lateral width of said support stake so that the entire end edge of each of said panels adjacent said stake is contiguous to the stake and when welded to the stake a tight seam is formed.