The high density foldaway shelving unit of the present invention includes at least one shelf and at least two spaced posts. The shelf is mounted between the posts. A pair of cantilevered floor mounts is mounted to the floor of a vehicle. Each of the posts is mounted to a respective one of the cantilevered floor mounts to transfer weight to the cantilevered floor mounts. A pre-assembled shelf mounting assembly is provided for mounting the shelves to the posts. The pre-assembled shelf mounting assembly has a bracket mounted to the posts, a pivot pin mounted to the shelf and a guide pin for stopping the shelf in the raised and lowered position.