I have read many articles and still clueless, so here goes.

The humming starts at 40 MPH and really doesn't change regardless of speed over that. Checked fluids in tranny and both differentials and they were fine. If I throw it into neutral while going over 40, the noise is still there. So what does that rule out? I have done a few S curves and the noise doesn't change or disappear, so guessing it's not a wheel bearing. Tranny is shifting when it is suppose to, so guessing that its not the problem either.

I left work one night and half way home a new squeal started and by the time I got home, it had stopped. So I blew it off. The next day I had the humming/whining/whirring noise start and it sounds like I am sitting over it.

Being a gal, I would like to have an idea of what it may be, before I start hitting up a mechanic to get quotes for a repair. Can't afford a new vehicle and have pampered this one for the 11 years I have owned her. Now we are both old and I just keep adding bandaids to keep her going.

 

Revving the engine while rolling at 40 mph while the transmission is in neutral makes no change to the noise rules out the engine as the cause. You're correct to rule out the wheel bearings as well. One thing that could cause the noise is worn out, chipped spider gears in the rear differential. When mine made a similar noise under the same conditions I removed the rear differential cover and found bad spider gears. Removing the cover and having them inspected is the first thing I'd check. If they're ok then you can cross changing your gear oil off your maintenance list and let us know.

 

Mine did a loud gear type humming noise which was the transfer case vac switch that took care of the problem.