Noise while driving from under truck. Any ideas?

[baycountry16]

Just today noticed a " nails on a chalkboard sound " coming from under truck while driving. That's the best way to describe the sound. Kind of sounds like the noise you would hear from squeaky brakes. Thing is, it only happens after letting off accelerator while coasting and also stops when brakes are applied. It is also intermittent but seemed to get a little worse and more frequent today. Any ideas what this could be? Thanks for any help as always!

[Karls03]

Sounds like a ring and pinion issue. Have you had any work done recently?