Been having a rattle since as long as I've had the car near the firewall on the right side (LHD US car). It sounds like its in the engine bay but I've never been able to track it down. It happens when the engine shakes a bit on idle or on shutdown. I've had half bridge and large street port engines, so things will shake a bit. I still have the ABS unit in that area and an engine damper. Anyone else ever have this?

 

Have you tried removing the engine damper to see if the sound goes away?
Check the heat shields around the turbo and downpipe area? some attached to engine others attached to the body.

 

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I'll try that. Been busy, separated from the wife so moving this car and my daily, and tools to my mom's house. 😭