Im driving around my dads 04' GMC Denali xl since my truck is in getting a new diff...anyways, bear with me on this, when im driving im hearing a grinding noise that comes at goes. and when it comes you can hear and feel it. The front diff was already replaced at 15000 miles (has 34K now). when i turn the wheel while im driving i hear it too. Its always the same speed the sound, it doesnt get faster or slower. just trying to troubleshoot this before my dads truck ends u p in the shop. please dont post just to bash gmc its only a question if anybody has had or knows anything about this.
-Thanks

 

maybe a wheel bearing?

 

Sounds like something that happened to my Jeep Wrangler when I had it. I kept telling the dealer guy that it was making a funny sound at a speed, I cant remeber now what speed it was. Well he told me it was a Jeep they make noise, I didnt like that answer! I took the diff cover off one day to see for myself what was going on in there and all this little shinny stuff came out in the diff fluid. My gears were ripping themself apart! Well I put the cover back on and told the dealership guy what was going on and he said, even though its under warrenty because I had 31" tires and stock was 30" thats what caused it and I would have to pay for it out of pocket. Well if I knew now what I didnt know then I would have raised major HELL! Long story short, check the diff cover. Place a magnet on the front cover for a day or so. DONT remove the magnet but do remove the cover. If there is any metal shavings at all you may need to have the ring and pinion gear replaced.