Thought I would get a better response from this subforum.
Have a bit of noise from the rear end. When above about 40, get a kind of "wuh-wuh-wuh" that increases in frequency with speed. At certain speeds, it gets a special pitch that makes things a bit louder (i.e. from ~56-58, 71-73). I realize there's a bit of brake noise in the second vid, but fairly sure that isn't what is causing it. I topped up the diff fluid last weekend (it ended taking about 400ml), and it seemed to help.
Any idea what the issue is?