Modular frame load handler with translatable boom carriage

A load handler with a modular frame and the manufacture and assembly of the frame and loader and components that may be used therein. A frame is provided that has a low pivot point for a boom. The frame has left and right side rails, and front and rear cross rails, each having a closed cross-section construction. The side rails and cross rails are modular and the cross rails of a selected size are configured to fit a plurality of sizes of side rails, such that the same size cross rails may be used to construct a variety sizes and capabilities of load handling vehicles in a flow type manufacturing process. A structural beam is provided having plates interconnected along their lengths to form the beam having a box-shaped closed cross-section having a perimeter generally along the widths of the plates and forming a beam cavity within the perimeter.