Can't wait to see this installed! That diff cover is going to POP on the rear end. Glad we could help get you setup!
I just came across those RPG Diff covers the other day! They look sick! I am torn on whether to go with black or the Fox shock orange color.
I am not sure if the RPG cover increases the fluid capacity or not. But on the Ford Performance cover, I normally go with 5 quarts because that cover does increase the capacity over stock—I normally have a full quart left over when changing the fluid on that particular cover.
Have you considered blue on your Gen 1? It would tie into the shocks nicely (if you've got stock shocks still).