1:58 Lol, you are replacing the diff cover so it doesn't matter if you get the fill plug loose 🙂 Yes it is always good to crack open the fill plug when working on the axles.
there has been mention that the ARB cover has a different volume amount than the stock cover. if you want to know for sure then before putting it on the vehicle install the ARB plug and dipstick then fill it with water then measure the volume. Do the same with your stock cover then compare.
I haven't seen an issue with it. I have replaced the fluid several times and have never had a problem with less fluid. I do know that I have ended up diff high on a couple of obstacles and this diff cover has saved me for sure.
Normally, stock gear oil took right at 2.5 bottles. (1 in the front, 1.5 in the rear) With the ARB, it takes about a full 3 bottles. (1 in the front, 2 in the rear).
