Ok ive did the search button and have got some ideas of what maybe this could be. i have an 05 gmc 4dr z71 in the last 2 weeks i have a strange noise coming from the rear of the truck it does it once im above 25-30 mph all the way up and only under acceleration and will do it on deceleration only time the noise will quit is when it seems like there is no load on the drivetrain I.E.like between downshifts and as soon as i let of gas on highway its like a hissing rubbing almost grinding but not quiet im thinking carrier bearing or pinion bearing and hoping not the whole rearend

 

ujoints maybe? Pull the diff cover and look for any obvious damage and abundance of metal in the fluid and on the magnet.

 

could very well be the carrier. The good thing about checking the rearend is that if nothing is wrong you're only out a couple qts of fluid.

 

Mine is making a metallic howling noise. Pinion bearing. If yours is too you may as well look into buying a used rear end cause prices to get it fixed are crazy.

 

mine is doing the exact same thing! has 130k miles on it.
i would think something with the pinion, but anyways changing out everything. getting rid of the g80 for an eaton posi, new gear, master install kit (bearings), axle bearings and seals.

 

well took it to the shop todat jacked it up on jackstands definently the pinion bearings dammit well dropped it off at the mechanic guess we will see how much this will cost. I wonder how much a new aftermarket rearend would cost bluecajun how much u droppin on all that??

 

Might as well put gears in it since he's going to be in there. If you haven't already.

 

Yea but if i do that its 4x4 so i would have to change the front also

 

OHHH right. didn't even notice that. Just looked at 18" and 35"s. " not ' (feet)

 

well thanks viciousknid i corrected it can i get a 100 on my test now please please teacher