I've got what sounds like a marble inside of a small plastic box being flipped and rolled around in one of my right side doors or B-pillar. It happens when I make a turn in the car, or make a hard acceleration from a stop or a hard stop. It doesn't happen all of the time. Almost as if whatever is rolling around gets stuck temporarily until a hard stop or turn jarrs it loose again.
Also, occassionally there would be a buzzing coming from around the right rear speaker, which I believe is the plastic somewhere around there rubbing against each other due to the vibration from the rumbling bass coming from the speaker. This happens more often in colder weather. I believe it's where the plastic from the C-pillar meets up with the ledge. I've had the fix for the rear ledge already done, but this problem still comes back once in a while, but not as much as before.
Everytime I bring in my car in and ask to have the "rolling marble" investigated, they take my car for a test drive to pinpoint where the sound is exactly coming from, and the "marble" stops rolling around. I've pulled open the bottom part of the B-pillar myself, but found nothing. I want to remove the inside door panels myself, but am hesitatnt of screwing something up that would prevent me from getting the inside door panels back on correctly.
The rear ledge thing doesn't bother me so much anymore...I just crank the volume on the stereo and then it goes away from too much vibration. But the "rolling marble" continues to piss me off!