Abstract: An outer extendable boom or extension is implemented on an extendable conveyor of conventional design, which includes at least two extendable units, each of which is nested within the next inwardly positioned unit and adjustably positioned between an extended position and a retracted position. The outer boom includes a pair of opposite side members which extend within an outer conventional extendable unit and a conveying surface. A support system is provided to support the outer boom as it extends and retracts within the outer extendable unit. A forward support member of the support system is laterally aligned with the side members and a cantilever support member is vertically spaced from a rearward end of the side members, such that a reduced range in width and a reduced range in height of the extendable units may be achieved.