Abstract: A flat bed side assembly including a barrier portion, a socket portion, a support portion and a holder portion; the barrier portion including a plurality of generally rectangular panels disposed generally vertically in an end to end relationship around the periphery of a flat bed; the socket portion including a plurality of pocket sections arranged around the periphery of the flat bed adjacent the lower edges of the panels, each of the pocket sections extending downwardly from a plane through the flat bed; the support portion including a plurality of elongated bar members having cross-sectional configurations substantially the same as those of the pocket sections, each bar member having its lower end disposed within one pocket section, the bar members extending upwardly from the pocket sections generally vertically; the holder portion including a plurality of bracket members with at least one bracket member engaging each of the bar members, each bracket member including a plate section, a strip section having