I have a 2003 CTS with 31xxx miles. Problem, I have a very strange rattle that seems to bounce around the front axle from side to side. My dealer could not find anything on 2 separate occasions. He even told me that the car was just settling.
I am confused. I don't always hear it but when I do it sounds like the front end is going to fall off. Note: no steering or handling problems at any speed ( knock on wood ) and I just had the struts replaced. Help!!!!!!!!!!

perhaps your cts is having the same problem my ls had, ball joints and such

Check front cradle bolts; I have found loose ones before. The front sway bar bushing clamps and ends make a lot of noise when they aren't snug.

You could do a search in all forums for 'rattle'. You might find something in a different car line post that'll give you a fresh idea.

I made this suggestion in a Lincoln forum; I'll repeat it here.

I've searched for a lot of rattles and noises in cars/trucks. Use a large rubber hammer for undercarriage rattles. It's an easy/cheap method to reproduce hitting a slight 'sharp' bounce and safer than hanging out the door by a seat belt or riding on the hood. Yep, done that too!

Good hunting!