ok. the friction tape trick did nothing. I'm positive now it's not the door seals.
Rich, I followed your tutorial and pried open the side panel. OMG what a pain in the ass. Not sure if it was because it was hot out, bad lighting, or such a cramped space to work (or all the above) but that was downright torturous to do.
What I discovered after tapping all over the place:
- there is a little round plastic threaded grommet (that has a speaker wire attached to it) was out of place. But I doubt it was the culprit since it's plastic
- my best guess was that it's the back of the speaker and/or the butler assembly hitting the rubber mat that is glued to the frame of the car that causes the rattle (reverberation against the frame). There seems to be a little bit of space between the rubber mat and the frame and that gap needed to be filled in
- I went crazy with felt tape and pretty much anything that wasn't backed by the fill-in sponge got some tape
Tomorrow will be the test drive. Will report back. Fingers crossed.