There are a lot of similarities between the LS and the Jaguar S type as they shared a lot of components during the early 2000s. You might want to try one of the Jag S type forums to see if others have had similar issues. That being said, don't discount the possibility of a foreign object having gotten between the sound insulation and the cabin under the car. Could be the heat shield has come loose but normally that causes a rattling not a rolling sound.

Did you look under the seat to find an empty soda can rolling around?

Sounds like a heat shield for the exhaust.

I don't see anything under there. Get a flashlight...

Hello!

Just bought a 2002 Lincoln ls 2 weeks ago and I'm slowly working up to getting it in great condition. Recently, within the last few days, I've noticed when I come to a complete stop and then drive off again I hear a rattling sound from what seems like under the drivers seat. It almost sounds like I have something heavy under my seat rolling backwards from the takeoff.

I've tried googling but couldn't find something similar. I'd like to know if I should abstain from driving until it gets fixed or if it's something minor I can ask my granddad to help with. In all other areas the car is in good condition with very small things to repair and clean.