A refuse compactor body has a tank section of an irregular polygonal right section that is uniform from end to end. The tank wall is made of rectangular pieces of thin very high tensile strength sheet metal and externally reinforced at spaced intervals longitudinally of the tank by polygonal peripherally continuous girth reinforcements, made up of straight short sections of metal tubes, to make a semi-monocoque structure. A floor portion of the tank is recessed between the longitudinal body support beams, which are the sole body support, to provide a relatively low center of gravity when mounted on a truck chassis. A hopper section of the body has a packer that obturates about two-thirds of the opening to the tank and is fitted at its upper edge with a follower that pivots to a shallower slope to keep refuse from falling behind the packer blade during a compaction stroke of the packer. In a fully extended position, the upper edge of the packer does not penetrate the tank entrance and so avoids excessive stresses on the tank roof at the entrance. In a retracted position of the hopper, the follower and the packer together define a sloping surface to deflect refuse towards the packing face of the packer.