Gentlemen - this is a public service announcement to check your nuts.
I had an odd scuffing / scraping noise from the rear end at speed accompanied by a slight creak or groan at slow speeds. I did some research and found that this was most often attributed to loose rear axle nut. I had the seals replaced by a reputable shop a few months ago, so I figured that couldn't be it.
Weeellll... on a whim I decided to pop the cotter pin and check. Sure enough. The nuts were pretty loose. I was amazed with how easily they could be turned with a standard socket wrench.
I went ahead and torqued them to the requisite 200+ ft/lbs of torque. Put it all back together and guess what? No more noise!
Ted