The stock differential covers on Jeeps are kinda thin. A thin gauge piece of stamped steel is all that protects your differential from trail obstacles. Slamming a rock up against the factory covers can dent them causing them to make contact with the ring gear within, an undesirable condition for sure. To make things worse usually the differential is the lowest point on the Jeep.
Dana 30 Factory Cover 
Dana 44 Factory Cover
There are several options for strengthening up and protecting this area. A simple solution is be very aware where the differential is and learn to judge height and go over obstacles to avoid contact. This only goes so far though.
There are many kinds of extra protection methods. Usually guards, armor and heavy duty covers are most common. Each have some advantages and disadvantages. For the jeepfan.com 2004 TJ Unlimited we chose competition covers from ARB which we picked up from Quadratec. These complete replacement covers look good, are composed of a thick nodular iron and relocate the fill hole to a higher point allowing some added protection as we as adding a drain plug for less messy oil removal. Check out the covers and comparisons.
Dana 30 ARB Cover 
Dana 44 ARB Cover 
Dana 30 Cover Comparison 
Dana 44 Cover Comparison
Installation
We installed the covers as part of an ARB Air Locker installation but the process is the same. Remove the factory cover bolts and gently separate the cover from the differential housing. The oil will quickly drain so have a pan handy. With the cover completely removed clean the housing surface.
oil draining 
clean the mounting surface
With the surface prepped spread silicone gasket material on the cover and allow it to set for a few minutes. Carefully position the cover and install all the bolts. Tighten a bit at a time while moving around for an even install.
gasket material on the cover 
front cover installed 
rear cover installed
Personally, we like to give the gasket time to set up before filling the differential with oil. One note with the ARB covers is that it is necessary to measure the height of the fill hole on the factory cover and transfer that to the ARB cover that uses a dip stick that is part of the fill plug. Make a note of the level on the dipstick. This measurement will mean that the differential will not be over filled.
Fill the differential with oil, check the level with the dipstick on the plug. Once the oil is in check for leaks and enjoy the nice look of the covers and have some extra piece of mind knowing your differentials are better protected.
ARB Competition Differential Cover for Dana 44
ARB Competition Differential Cover for Dana 30
