Is it a squeeck more than a rattle? does your spyder have Sun and sound (leather basiaclly)?? Is it a 5spd?? The 5spd throw out bearing rattle at idle when the clutch is not pressed down. the leather seats will develope a slight sqeeck\ rattle to them.

Is your dash cracked? most 3G eclipse have cracked dashboards? maybe something to so with that? can you tell if it is an inside or engine bay noise?

 

Wow is there a recall or something on these dashes, cuz that is what seems to be rattling. Also, this started right after I had taken my car in to have the stereo removed so they could get me a code, I bought it used and the dealer did not get the code from the previous owner and it had become locked after the battery was replaced. I picked up a bolt that was on the floorboard and took it back and the service advisor popped it in the dash right beneath the stereo so it makes me wonder if they failedtoput anymore back in correctly.

 

I dont think there is a recall.. But it does happen to 90% of the 2000-2005 Eclipses. They always crack