Getting my gears changed to 5.38 next week along with Coast DS's, EVO C-gussets/sleeves and better ball joints but the question I had was after getting new diff covers such as Riddler's, does the amount of gear oil that needs to be swapped out change as well? I know some covers allow for more fluid depending on the size and where the fill hole is located. Thanks in advance!

 

With a different cover, you can't go by the number of quarts in the differential.
The important thing is to get the oil level above the bottom of the axle tube, so it can lube the outer axle bearings in the rear, and lube the carrier bearings in the front axle.

Here is a picture showing the oil level as it relates to the OEM cover.
You can make a dip stick out of a zip tie. Try to get the same level with your new cover using the dip stick.

 

thanks for the reply. Is there any issues that could arise from filling any cover up the fill hole?

 

Some covers have the fill hole way too high for some situations.
Too much fluid may foam, which is bad for proper lubrication, and will spew out the vent tube.