a lot of us had this rattle. it is the screw that holds the B pillar (the vertical part that the window rests against). i cannot find the post that best describes what is happening). you need to remove the plastic piece where the seat belt comes out (see articles). then you will find the screw that needs to be tightened. do not over tighten. i broke mine off, but likely the rattle is still gone (2 years later). do a search and you should more detailed info.