I was convinced that somewhere in the life of my newly acquired 2002 LS6 that the driver's window had been broken and replaced and the the shop/person doing the work was lazy in getting all the glass out of the door. Annoyed by the continuing rattle, I decided to remove the Door Panel and do the job correctly (YouTube was my friend here). I was slightly amused to find that the door was sans glass but almost every bolt holding the innards on was loose. One even fell to the ground as I pulled the panel off. I was also pleasantly surprised to get it off without breaking a single push tab. The rattle I hear from the passenger Door Panel compelled me to remove it and tighten them as well although they were not nearly as loose as the drivers side. Had the passenger side off in under 10 minutes I tell you.
https://www.youtube.com/watch?v=C9mPqqkDGrU
https://www.youtube.com/watch?v=C9mPqqkDGrU