2009 GMC Acadia "constant rattling under front end" Questions

...rattling noise on the front driver's side only. Any ideas? It sounds like you have a bad c v or constant velocity joint. Look under the car next to the wheel look for a rubber accordian type unit, if ...

...constant? Try checking the heat shield at the catalytic converter. These sometimes come loose and make a rattling noise when the engine is running. This is probably the heat shield. The shield is a ...