Any suggestions......I have a 2003 Ford Explorer with less than 60k miles. I get a slight vibration in the back end of the SUV when completely stopped and making a left hand turn. It has gone to ford and they added some kind of fluid to the rear differential but that was only 10 months ago and now it is doing it again. Also getting a whistle/whine from front end of vehicle when going between 35 and 70 mph that comes and goes. Any suggestions to bring to FORD. They say nothing is wrong?