Hi, I'm back from the dead.

The Trooper has 263,000 miles on it and is still going strong. For, oh, maybe the last 50k miles or so I've had this odd "hooting" noise coming from the back end. Sounds like the brakes but it's hard to tell. When I take a turn (sometimes) OR when I side-load the truck and roll it in the driveway, I get a sound that can only be described as an owl hooting. Lasts as long as the loading is present when it decides to do it.

The hubs seem solid in place (i.e. no lateral play) and a brake job seems to fix it for a short time (the 91 does have discs in rear). This is the OE corp axle with nothing more than a diff fluid change around 170k miles. No leaks.

Any ideas?