I'm new to the forum so I hope this is the best place to ask this question!

I have an 07 1500 Classic Z71 that has a noise coming from what I believe to be the front end. It sounds like a tire roar or maybe the front end is not disengaged. All fluids are topped off (tranny, front/rear end, transfer case). The only slack I can find anywhere is in the drivers side front axle on the differential side, but there is no oil leaking around the seal to speak of. I have been told by a Chevy mechanic this may be normal. I replaced the driver side front hub, which had slack and grease coming out of it, but nothing has changed. The noise is present from about 10-35 mph, and goes AWAY when the truck is coasting and put in neutral. Comes right back as soon as it is put in drive again. 4wd is not engaged (driveline free in park) and there is a noticable change in sound when the 4wd is engaged.

Other than taking it top the local dealer, I'm kinda stumped! We are going to put it on a lift this weekend and attempt to pinpoint the noise. Any other troubleshooting ideas would be greatly appreciated!

 

My 2014 Chevrolet Silverado LT Crew Cab Z71 is doing the same thing. Any ideas?