dragging noise from underneath truck - This forum was quite helpful once before so I am returning to the well for more advice! I have a 2003 GMC Sierra 4x4 ...

This forum was quite helpful once before so I am returning to the well for more advice! I have a 2003 GMC Sierra 4x4 Z71 extend cab shot bed that has started sounding like it is dragging a chain.

We were towing a very light trailer (appx. 1200lbs) and were cruising through a campground at about 20 mph and heard what sounded like us dragging safety chains. Got out and checked and we weren't dragging anything.

The noise only happens at low speeds (20-25mph)
the noise isn't associated with pressing the breaks
The noise isn't associated with a particular gear or RPM
The noise seems to happen whether the gas peddle is being pressed or not
It happens whether towing or not but is louder and more pronounced when towing a trailer.

Any ideas? I have googled and googled and SO many different things come up that I don't know what to think.

Thanks much in advance for your help.

My 99 silverado made a noise similar to chains. I could hear it while idleing. As I would drive you can slowly hear a winding then getting louder as I speed up. It turned out to be the 3 bearing on the rear end. Some were broken moving around and thats what made that clinging noise. After replacing 3 of them near the differential the noise stopped, but it did take a mile or two for the new bearing to get broken in. The cheapist way to find out if you have any rear-end problem is to buy rear-end fluid. Then drain the fluid and look for metal shavings. If so then you know that you have a promblem.