Bumping this back up. I thought I had a line on an Alloy USA cover but it fell through. They suggested a Tereflex cover instead. Any newer thoughts on Dana 30 covers anyone?
TeraFlex 3990630 Differential Cover Kit (Dana 30 HD) https://www.amazon.com/dp/B006D9WGKE/?tag=wranglerorg-20
I have one - bought it from "Amazon Warehouse" for about half that asking price. Seems as good as anything else, certainly heavy duty, blah, blah, blah... Give it a paint re-spray before you mount it up - paint on it is starting to rust through on mine after 2 years.
Oh - and the drain plug that came with it didn't seal well - I guess some cheap Chinese thing that didn't have enough taper. I replaced it with another one from the hardware store (be sure to get an Allen key style for flush fit), and no more problems. YMMV and all that.