I've got a 2006 with a manual that is making a grinding noise. The noise sounds like 2 plates rubbing/scraping together. It only occurs once in gear [3,4,5] and once I've lifted off the gas pedal. Only feeling a slight vibration thru the clutch pedal. My truck has only got 25000 miles and I only use it to pull my 30ft. travel trailer[9000lbs]. Could this be the throw-out bearing or possibly something else. Any input will be greatly appreciated.