Abstract: A planetary differential assembly for selectively locking a pair of coaxially aligned vehicular axles for driving the axles at same rotational speeds. The assembly incorporates an axially moveable locking ring having an annular central body and first and second axially extending coupling portions spaced radially apart about inner and outer diametric portions of the body. One of the coupling portions is adapted to receive a shift actuator flange for axial displacement of the locking ring between engaged and disengaged positions of the differential. In a preferred form, the radially innermost coupling portion of the locking ring continuously engages and is axially displaceable on a sun gear, while the radially outer coupling portion of the locking ring is selectively engageable with a splined planetary carrier.