My 2007 5.9 6 speed manual has always had that normal rattle at Shut down. THat kind of shaking of the truck you might say. These last few days its been over 100+ degrees here and NOT cooling off much at night. ( Upper 70's-Low 80's). I noticed that at START UP my truck ' feels' like it is rattling the same as when I shut it down. Idles fine, starts right up, no performance issues. I had a buddy start it up for me tonight and I listened with hood up and once bending down under passenger door to see if I could hear anything externally. All sounded fine. I wonder, is this ' feeling/noise' related to the Dual Mass Fly wheel wearing out? I was thinking maybe the parts just aren't cooling off at all between restarts so that could be the issue? Definately no smoke and not an injector issue at all. Thanks!