RC Industries Underbody Tool Box V-Series Vertical 18x24x18 Steel Textured Matte Black Curbside Model VM182418.SC 99 Gallon and accepts the male pipe

and accepts the male pipe end #28931 or #28932

That is the size you will want to order (and this rack will be about 12" tall to account for the 5" of the Magnum bed rail kit)

2011-2018 Ram 2500 76

Steelcraft Bed Rails Model 613407

8 2017 GMC Sierra 2500 HD 78

RC Industries Underbody Tool Box V-Series Vertical 18x24x18 Steel Textured Matte Black Curbside Model VM182418.SC 99 Gallon and accepts the male pipeRC Industries Underbody Tool Box V Series 18x24x18 Steel Textured Matte Black Curbside Model VM182418. SC RC Industries is well known for building the highest quality tool boxes in the industry. RC utilizes more bend lines and fewer welds to eliminate leak points. Their hardware and fasteners utilize heavier gauge stainless steel for rust prevention, and they choose parts for durability rather than for price. The powder coating is specified for