i have this rattle in the exhaust sheild located but the catylic converter and i shook the exhaust pipe and hear alittle rattle but touched the sheild seems alittle louder but seems to get worst every week. the exhaust shield doesnt seem loose.
I use a rubber mallet to tap on the pipe to determin where the rattle is coming from. Use can use a large hose clamp on the shield if thats where it's coming from. If the shields don't look loose it mabe coming from inside the cat, it could be coming apart.
I have also seen the metal tag on the convertor under the shield come loose. You can cut the welds and fish out the tag and then clamp the shield back on.