I've got a rattle coming from the back (likely tailgate) that I can't track down for the life of me - will have to try this. It's not a squeak, it's a rattle. I pulled the panel off and got in there with a vacuum to get the bits of rust and other stuff out thinking that may be it (the area around where the license plate mounts on one side was/is quite rusted which is where a majority of it came from). I'm going to have to get in there again and poke around for anything loose.

I checked to make sure the panel doors for the passenger side storage and the drives side jack storage and the jack itself is secure, made sure the roof rack is secure etc. I do drive with the back seat down 99% of the time since it's typically dogs and hunting gear when there is something in the back which may contribute but everything seems pretty firm there.

Any other ideas of common rattles from back there welcome!