Load storage enhancement apparatus for a truck having a rear storage platform or bed, the combination comprising two extension walls that have generally horizontally stored positions over the platform and generally upright extended positions projecting above opposite sides of the platform, framework attached to the walls in their upright positions, the framework including members extending laterally and supported by the walls at locations spaced both lengthwise and widthwise of the upright walls, the members blocking tilting of the walls, and mechanism resisting pivoting of the walls in upright positions. Elongated carrier structure is adjustably movable between extended position over a truck cab, and retracted position over the truck bed, to be locked in either or both of such positions. Carrier structure guides on the walls move with the walls between upright and lowered positions.