If you can install a set of brakes you can install the Aussie Locker®.
The "Aussie Locker"® is the most relied on differential on the market today. Trusted by offroad enthusiasts to get their vehicle in and out of every possible situation the "Aussie Locker"® delivers performance.
The true automatic locker.
A simple design with no actions required by the driver to actuate the locking capability. There are no cables, electrical wires, air lines, pneumatic or external connections of any kind required.
Safe offroad and on.
Unlike manual lockers which do not provide differential action when locked and severely hamper steering and directional maneuverability, the "Aussie Locker®’s" smooth and sensitive operation allows differential action resulting in uncompromised steering, uphill or down, soft or hard surfaces. Even on highway driving the "Aussie Locker"® does not impede performance
See http://reviews.jeepforum.com/showproduct.php?product=19&cat=47 for more reviews.