Loud noise coming from under the truck 07 sierra

[chadt256]

My 07 sierra nnbs has a weird but pretty loud noise when i am backing up its like a vibrating noise coming from the middle of the truck it sounds like the driveshaft is coming apart or a heat shield is loose but cant find anything? and also when im slowing down around 20mph it rattles and vibrates again? its about to drive me insane!

[oleshifty]

sounds like a u joint. Jack the rear end up by the pumpkin til tires come off ground...try moving shaft...lower it a little and repeat. If shaft moves at all, replace em. if its a 2wd ext cab or larger, could also be a carrier bearing.

[chadt256]

well thats what i thought.. but i can put it in neutral and it still does it ? it feels like it coming from under the back passenger floor board its vibrating and like a loud clunk or something very hard to describe!

[EmmerichLSx]

Maybe your exhaust is vibrating on something.

[oleshifty]

rear end/tailshaft is still turning in neutral... if vehicle is moving

[Jordan836]

Is it possible your exhaust is vibrating on the metal bar that is bolted from once side of the frame to the other, im pretty sure its so if the drive shaft fails it doesn't hit the ground. And it might be the center carrier bearing next time you drive see if the noise goes in sequence with the bumps in the road and if it does then thats a good sign it could be the center carrier bearing.

[chadt256]

thanks im gonna check all that out when i get a chance.. ive looked over and pretty sure its not the exhaust it may be that carrier bearing thats where the noise sounds like its coming from.

[Ray@NP]

Check It Out I Just Had A Truck Do That And It Had Rocks Stuck In The Trans Mount, I Removed All The Rocks And Noise Went Away, Sound Crazy But Its True Man Id Look At That