I had the same problem with my denali. Had it repaired yesterday cost my 450.00. The carrier bearing in the front differntial where wearing out.I unscrewed my drain plug for the gear oil and it was swimming in metal. check the magnet on the end of the drain plug for metal. This was on a 01 denali with 65K miles. It want go away it will only get worst. Get it repaired before you have to replace the front ring & pinion