2003 Toyota Highlander Rear End Squeak

I have a 2003 Highlander 2wd with 113000 miles. Recently a very high pitched squeak/squeal began to develop in the rear end at highway speeds. The noise goes away when the vehicle merges from left to right or if making a right hand turn, or when even minor pressure is applied to the brake pedal. I have inspected the rear breaks. Pads are nearly new and rotors are wearing evenly. Just as a precaution, while I had the calipers removed, I removed the rotors and had them “turned”. The squeak went away for about a week and now is back. It almost sounds like a break pad squealer, but it isn’t. I think that we have isolated the noise to the left rear. I have seen a TSB that says there is a rear axle squeak problem with 2003 Highlanders. I can’t ascertain if this is just for 4wd models involving a faulty oil seal or if it applies to 2wd as well. I don’t think its the axle because it goes away when the breaks are even tapped. Any suggestions/ideas? Struts? Bearings? HELP!

Thanks…