Just wanted to share w/you all about the fix and hopefully help someone else out. My 4Runner sat for a while, many months, thus warping the rotors. Has them shaved and all is well with that area. The sound from the rear also happens on a number of other dual axle Toyota vehicles. It's something to do with the suspension and axle and a known issue, butno problem. I had a Toyota repair man drive w/me and when I told him about the noise, he knew exactly what it was. So if you have this, there should be no issues or problems. Hope this helps someone.

R.