The Aussie Locker XD-13027 is an automatic locker for Dana 30 27 spline axles with open carriers. A "lunchbox" type device, it replaces the internal parts of the stock carrier. It needs to be installed in an open differential. If the axle already has an LSD, it will need to be converted to an open differential prior to the Aussie Locker installation. No ring and pinion gear set up is required and installation shouldn't take more than a few hours.