A float gauge assembly for a storage tank having a port with an opening includes a body for attachment to the port of the storage tank and a gauge mountable to the body, the gauge having a gauge face for indicating a level or amount of material present in the storage tank, a float mechanism mounted to the body and cooperating with the gauge, the float mechanism including a float movable relative to the body in an operating position, the float being sized so that the float is unable to be inserted into the storage tank though the opening in the port, and a tube coupled to the float and having a dimension sized for inserting through the opening in the port, and an alignment element configured to rotationally fix the tube to the body when the float is in the operating position so that the gauge face accurately indicates the level of material in the storage tank when mounted to the body.