Abstract: A vehicle transfer case for changing between two- and four-wheel modes of operation has a transmission with an inventive stop. The stop extends radially outwardly beyond the nominal height of gear teeth on a worm gear in the transmission. The stop engages a worm which is part of the transmission at a location outside of a primary contact area between the worm and worm gear. When the stop contacts the worm it stops further rotation of the worm gear. The motor for the worm gear is reversible such that both the worm and worm gear can rotate in either direction. A single stop defines two circumferentially spaced ends of travel. Since the stop contacts a moving surface on the worm, there is a reduced likelihood of seizure when compared to the prior art.