I have a 99 OBW, 2.5 auto, about 187,000 miles. It has had a very noticeable whine while driving for some time, sounds exactly like tires with a pattern worn into them, present at all speeds and gets a bit louder at higher speeds. I just replaced all four tires and both front axles with new and the whine is still there. Lube levels are OK, but fluids have not been changed for awhile. Is this something with the rear driveshaft, it’s hard to pinpoint where the sound is coming from.

If it's more drone than whine, likely a wheel bearing.

 

Does it change with the amount of throttle? That would make it a driveshaft or pinion bearing.

It seems to be speed dependant but not load dependant. I don't notice any change in tone when turning corners like i would expect with a wheel bearing.