2007 LaCrosse rear end clunk

My wife's Lacrosse has this clunk in the rear I hear when going over a small bump or on occasion just when the suspension moves slightly. It actually sounds like it is coming from the trunk. I have checked for anything loose.... suspension, shocks, brakes, muffler hangers, inside the empty trunk, spare, etc. and can find nothing loose or hanging. Anybody have any ideas? Thanks.

EDIT...Well after five days, and 161 reads, I guess no one has has this problem or any ideas. Thanks anyway.

My 2008 does the same thing only on a right turn sounds like it is coming from trunk, oddly enough i have only ever had it happen at the corner near my house never anywhere else and I have noticed "wear groves" in the road where everyone tracks but it doesnt make sense it is very intermittent and I think it may be on this one right turn becuase it is a pretty sharp right but still can't figure it out. I think it has to do with speed of the turn.

My 2008 does the same thing only on a right turn sounds like it is coming from trunk, oddly enough i have only ever had it happen at the corner near my house never anywhere else and I have noticed "wear groves" in the road where everyone tracks but it doesnt make sense it is very intermittent and I think it may be on this one right turn becuase it is a pretty sharp right but still can't figure it out. I think it has to do with speed of the turn.

Is this something you were thinking about getting looked into, jjchevy? I understand if not, just wanted to state that if you work with a dealership on this I'm available to assist in that process in whatever way I can.

Best,
Sarah
GM Customer Service