Probably not the problem but check the sway bar links, they can make all kinds of racket when they go bad. If the boots are torn or missing the link is shot. Also take the old links off and make sure the ball joint is stiff. If it's floppy or loose then it's time for new ones. Also look at the sway bar bushings. The exhaust could also be hitting something.

I've also experience weird noises from things bumping around in the way back in my wagon or in the truck. So make sure the spare is secure, and the jack, and anything else you have back there.

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