An adjustable nut comprises a main body having an axial passageway and a locking insert. First and second wing members are pivotally mounted to the main body, whereby the wing members include respective cam surfaces that deflect the inner surface of the locking insert toward the threaded shaft. The assembly provides three different mounting arrangements. The first and second wing members are adapted to provide (1) a locking position where the main body is immovably locked to the threaded shaft, (2) an adjustment position where the first wing member is in the locking position and the second wing member is in an unlocking position to permit selective adjustment of the main body with respect to the threaded shaft, and (3) a sliding position where the first and second wing members are in an unlocking position to permit the main body to slide axially along the threaded member.