The ARB differential lock can be retrofitted. The major advantage of this selectable lock is that the differential functions like an open one in road traffic.

No unnecessary tire wear - no unexpected intervention of the differential lock *
Off-road, when the situation demands it, the differential lock can be engaged at the touch of a button within 1/10 of a second, with 100% effectiveness. Installation is straightforward; only the differential housing needs to be replaced. The compressor required for the system provides the necessary pressure to lock the differential at the push of a button.
When switched on, a ring piston built into the differential is actuated, locking the differential. When switched off again, the compressed air escapes from the solenoid valve and small high-performance springs release the retaining ring. The differential then functions as a normal "open" differential.
*For vehicles up to '97 with 45 mm bearing journals, two additional bearings 2-160116 with an 80 mm outer diameter are required!*
*In rare cases, bearings 2-160118 with a 50mm journal diameter and an 83mm outer ring diameter are required. e.g., HDJ80*
Danger:
Any accessories shown, such as ball, roller and cylinder bearings, are not included in the scope of delivery.
Installation should generally be carried out by a specialist workshop. If a manufacturer-installed original differential lock is present, it cannot usually be replaced with an ARB airlocker, or only with considerable effort.