A cargo rack includes a frame having a front, a rear, and upper and lower end portions. The lower end portion has a base with a floor providing a load holding position. A tank module that is supported with the frame during use, the lower end portion of the tank module resting upon the load holding position of the base. The frame includes a plurality of side walls that attach to and extend upwardly from the base frame. Each side wall has a pair of corner columns, a central plate, and a plurality of diagonal members, each diagonal member connected to a corner column and a central plate. The frame can include at least one horizontally extending beam connecting between each pair of corner columns. The diagonal members include an upper pair that can form an obtuse angle and a lower pair that can form an acute angle.