Ping noise from rear of truck on 2002 Chevrolet Silverado 1500

After stopping at a light or a stop sign when I take off I hear a pinging noise and I think it is coming from the rear end. I have had this truck since 2003 and it has done this ever since. Do you know what it could be.

Asked by for the 2002 Chevrolet Silverado 1500
As for the noise, it is really hard to tell with out being there, it could be shocks, a loose or broken bed hold down bolt, a broken spring etc. Have someone ride in the bed to listen and then make the noise happen. That is often what I have to do in the shop to isolate noises, that is what I did when I worked as a GM Dealership Technician. It really works.