HI im new to this whole forum deal I recently baught myself a 2001 gmc sierra 1500 c3 all wheel drive (always 4x4) basically is an all wheel denali I found that when I take longer drives 25 minutes or more I end up with a powerful clunk along with the rear tires chirping when I turn corners it feels so rough I feel like something is going to snap I did have a back yard mechanic look at it he recomended II drain the old fluid in my t case and put lucas and dex lll I did that and he did the diff still experiencing this issue when I drive longer distance any idea'* he also did recommend u joints becouse of play in the axel and t case any ideas is it worth fixing ?? Please help baby'* due soon and it'* our only family vehicle at the moment :o