Our dealer installed an aftermarket class 3 hitch on our 08 acadia. Although we've had it in the shop twice he claims they can't hear the rattling noise that is caused by the hitch. We think that a.) the hitch itself is loose (scary thought, though we haven't towed the boat yet) or b.) the exhaust is loose somehow. The salesman claims that everything it tight and working properly, anyone else had an after market hitch installed? It is obvious when going over a pothole or even a speedbump.