Curious if anyone can help with suggestions on diagnosing this annoying rear seat rattle coming from my '21 Tahoe. I've mentioned it to the dealer 3 times when brought in for service/recall. First two times, they same they "tightened something" but it was never it and last time they said they "can't reproduce the rattle" so nothing they can do. Granted it doesn't ALWAYS make the rattle but very often. Also seems to have no preference for smooth vs bumpy roads. When it decides to rattle it just rattles and won't stop.