I bought the kit from AB for both diffs and the t-case.

First off, the rear plug they sent was for the newer (I'm guessing) plug and thus was larger and had the hexagonal hole. So I couldn't do the rear diff. I did however sample a few drips from the fill plug and make sure I didn't have coffee grounds. Rear diff is fine for now as the fluid is not that bad, relatively clean-ish.

Now the fun starts. I was using a fluid transfer pump to fill the front diff, and foolishly used the tiniest fitting, thus increasing the amount of oil pressure in the pump. Fitting explodes off, and I lose count of how much oil goes into the diff. I end up filling it up to the fill plug, despite how many places I read NOT to do that and to instead put 0.61L in. I worry all night, and end up draining a little bit to be on the safe side. I found a thread with some saying a little extra over the recommended amount wouldn't hurt.

Drove home about 60 miles this evening and a block from my house hear a BANG of sorts, kind of like someone shooting a pellet gun from the area around my drivers side wheel.... right where the diff fill plug is. I freak out and stop to check all the plugs. No leaks, plugs are fine. Still unsure I turn in for the night. I wake up later and on a hunch go outside to inspect the area again. Found little specs of oil splattered inside my wheel well. Oh no...

Sure enough the front diff's breather had long since become blocked and lacked the updated gore-tex service bulletin fix. Somewhere on the line, lower down, I had blown the breather out of the diff. Guess I'm calling my tech in the morning...

Moral of the story, don't fill your diff to the plug unless you are 100% sure you have a good breather. I didn't see the signs (fill plug literally blowing out of the socket as you remove it), and didn't fully consider what the oil expansion would do.

Thanks to BByer, I read through a lot of your old forum posts on the topic, unfortunately got to the breather posts after the fact.

 

My 05 has those plugs that take as metric hex key

When I serviced mine I unhooked the breathers, blew em out with compressed air and blew into rear through the fitting mine was all good, asked my dealer tech if I need to do the update, he stated they realty do not do them, just blow out lines like I did