JeePerf COMPLETE Differential Drop System for Jeep WK2 lifted 2" or more. 
Your IRS differential is mounted to your chassis and is coupled to your wheels by half axles that use CV joints to transfer the motion. When you lift your WK2, you are effectively furthering the vertical distance between your chassis and your wheels by that much height of your lift. What this does is increase both the distance AND the angle of any component connected between your chassis and your drivetrain. That includes your Rear wheel drive system which, in this case, is driven by your half axles.  
Half axles are designed by factory engineers to handle the angles imposed by a flexing suspension WITHIN specified design range parameters. When you lift your vehicle, you put your drive train outside its normal design range if operation, forcing your CV joints to operate at steeper angles than what they were designed for. This causes accelerated wear on your half axles, and you end up having to replace your axles more frequently than you want. 
There are two solutions to solve such a problem. They both revolve around making your front axles' CVs operate WITHIN their design range. 
The first solution is to install very high end CV joints, designed to operate at steeper angles. Those tend to be highly specialized, in short supply, expensive to purchase and are custom built which usually take a longer time than you are willing to wait. Due to their highly specialized nature, those can also be discontinued at any time due to their high cost to build and according to market demand. 
The second solution is to drop your whole differential down to bring your OEM axles’ CV joints back to their normal design range of operation. This solution tends to be a simpler, more elegant, more direct and more cost effective approach to solve the same problem. This solution will require no special maintenance and is an install-and-forget approach to solve the same problem. 
This is the approach we took and we succeeded in finding such a solution. Introducing our Rear differential drop system. It shifts the angles of operation of your CV joints back to their NORMAL operating range, to eliminate vibration and reduce excessive OEM CV joint wear. With our solution, you end up having your desired lift AND NOT HAVING TO UPGRADE OR FREQUENTLY REPLACE YOUR CV AXLES. This solution is simple to install and, once installed, it requires no special maintenance. 
This differential drop system comes with custom built narrow profile differential bushings and WILL NOT WORK WITH OEM STYLE BUSHINGS. The bushings we offer are NARROWER and made of Soft, Long Life PU. They are designed to have low NVH, have a long service life and need no maintenance.
This diff drop system is highly recommended for 2" lifts and above.