My 2017 LTD had a noise, which sounded like a rattle, coming from the right middle row seat. I wrapped electrical tape around the metal to metal parts - no luck. As I concentrated on the "rattle", the noise seemed to travel. I stuck foam (the type like you stick between window sashes when installing a window air conditioning unit in your house) into every crack and crevice I could find. No luck. I found that the headliner attaches with magnets and I could pull it down a little and stick some of the foam into that area and sometimes it would stop for a while - not a cure. I finally, while riding around the neighborhood, saw my neighbor and his wife and inquired (since my wife said she couldn't hear anything - but accuses me of not being able to hear) as to whether either of them could hear really well. His wife jumped in the front passenger seat and before we got out of the driveway, she said "it's back there (pointing to the back). She went to the back and we left and she said, "it's the seatbelt - right where it fastens to the side". Took her back home and stuffed foam all around that area - still "rattled". I folded the seat down looking again and saw two metal "U" shaped metal clamps holding the lower cushion to the frame of the lower portion of the seat which were only exposed when the seat was folded about 1/2 way down. Brain said - "That might be it". Got some white lithium grease (in a tub) out of my shed and, with my right index finger smeared a thin coat on each of these "clamps". Set the seat back into its normal position and no more "rattle" - which was actually the leather upper (back) of the seat rubbing on the metal. It was a squeak disguised as a rattle. I have reapplied once since then as the leather soaked it up, but it's an easy fix. Like driving a new vehicle.