[Quartz]

I have not needed an aftermarket cover. The only reason I see for it is more oil.

 

[kewlkarim]

well, it does hold more oil, and the more oil you have the smother & cooler your rear diff will be.

 

[nissankidd]

Its helps to keep the rear diff cool and increases oil capacity.

 

[gary748]

Not really much to explain with an aftermarket differential cover. The main reasons folks purchase them are:
-Looks
-Higher capacity-means more fluid and theoretically lower operating temps.
-Easier maintenance. The Mag-Hytec I have has a reusable gasket and dipstick for checking fluid level. Other brands do not and some lack the brake line bracket like the OEM unit