Air Locker locking differentials allow you to tackle the toughest terrain. As the world's premier traction aid, ARB Air Lockers keep you moving in all conditions. While developing the Air Locker for the 2012 T6 Ranger and Mazda BT50, ARB Engineers noted the similarities between the differential dimensions with the Landrover Discovery Series 3. With the only difference being the ring gear diameter, this resulted in development of the RD217. This Air Locker fits the front axle of the Land Rover Discovery 3 and 4. The Air Locker for the rear axle followed. The RD218 was developed so that customers have the opportunity to lock both axles of their Discovery 3s. Because Discovery 3 are built with IRS systems, the removal and installation of the differential assembly consumes more time that a typical live axle vehicle. Furthermore, as the rear section of the exhaust system is mounted underneath the axles, it will need to be removed before carrying out the above. Adequate time should be allocated for RD218 fitting, but overall complexity level is relatively low. Due to variation between the rear axles of the Discovery 3 and 4, the RD218 only applicable for the Discovery 3. Please also note that it does not suit vehicles with an original equipment, O.E., differential locker.