"clunking" sounds from the rear, when going over bumps or through potholes, can also be the bushings in your track control arms going out. Your warranty won't replace those either because it doesn't pose a safety problem and the arm itself does not break or wear out, just the bushing.
I'm about to tear the entire front and rear suspension out and replace every bit of it. $3000 in parts and a complete weekend of bloody knuckles and swearing, but doggonit, I won't have to worry about this crap for a long, long time afterward.