hey all-
well like most of you, i was going nuts with a rattle from the b pillar on the driver's side. i scoured the internet and addressed any possible culprits (seatbelt, adjuster slide, etc etc). after about 12 hours i was finally able to isolate it, and it was a place i never would have considered. picture is attached, but the long story short is that there was something weak about the piece that's welded to the b pillar, specifically the small metal brace that routes the seatbelt from the coil down low to the top. i found that if i PULLED on that small piece of metal, the sound would go away.
so instead of having it re-welded, i was able to pull it back enough to jam some felt tape in there. that solved a lot of it, but i was still hearing a rattle. the next step, and what fixed it 100%, was to jam a small washer up the tiny gap at the TOP of the brace. no kidding i took a small, maybe 1/2 inch washer and packed it up there with a screwdriver, which replicated the pulling motion i was doing to it earlier. so it's a caveman fix for sure, but it worked. i also packed a bunch of silicon gel up in the gap, assuming that over time the washer would work itself loose and i'd have a whole new rattle to deal with.
hadn't seen the weld issue on any tesla specific sites but did see some threads out there with camrys etc. but this definitely fixed it. hit me up with any questions, absolutely willing to help out as i realize how frustrating it is to drop that much $$$ on a car and have it start rattling.. picture attached, worth a 1000 words..
PS the pic attached is just some stock photo i found, i forgot to take a picture of my own car before i put it back together