I'm not sure what the problem could be. When my Jeep gets warmed up, there is a high pitched grinding sound that comes from the front (possible t-case or tranny). The sound comes when I am accelerating or after I downshift. When in neutral or while shifting gears, the sound disappears but then comes right back once in gear. About a year ago a mechanic told me that there was a rear diff leak, but I took it to another about 3 months ago and they said he was an idiot haha. What could this be? It has been driving me crazy lately.