2014 RDX with 422K miles.

I have an annoying rattle from the rear. I thought it is coming from the rear spoiler. Don't know if it is called something else. It on the top above the rear window.
There is some play to it when I shake it.
Removed the molding on the inside looking for something loose that I can tighten. Nothing loose.
I wonder if it from the suspension as I had not replaced the rear shocks, sway bar links and bushings since the car was new.
But I hear it coming from the rear towards the top. I think but not 100% sure. When I push down on the back of the car, there is some play up and down. May be shocks are due for replacement.
Any ideas what I could do to fix this?
Thanks.

 

You should also check your spare tire, The spare in my wife's 2016 had worked it's way loose and was making noise. Just a thought.

 

Thanks for the suggestion.

Checked. The spare is practically immovable.

 

Okay - well with 400K+ on the odometer, I would get it up on a rack and shake any and all suspension components to see if you can narrow it down. Again at 400K and if all original, it could me lots of things and or a combination of things.