Figured out my squeaky squeaky on my driver's side rear suspension of the G8. I really thought I had another bum strut/shock from rock auto. This issue was really prevalent when I have the 20" wheels.
There are two bolts. One that mount the strut to the LCA, and one that mounts the hub to the LCA. Both bolts look identical. Both are 18mm heads.... however one is roughly 3.75" (this is meant for the hub to LCA) and the other is 4" (for the strut to LCA). So it's quite easy to mix them up.
So, if you inadvertently put the 4" on through the hub, it just scrapes against the trailing arm. That was the noise I was getting.
So I swapped them around and now have silence...
Here it is before. The 4" through the hub, hitting the trailing arm.
Fixed
Also, technically the strut bolt should be going the other way from all the pics I saw online, so I did the same.