Just got it back....
They did a fix on the Marker Lamps that included double sided tape, wedges, and they replaced the screws with "bigger" ones. Don't know what they meant by bigger. I can't see any differences from the outside. They told me that this is not a GM fix. This is their own fix. They say they have had good luck with it soi far.
Also....
The 1800 RPM growl was fixed. They said the heat sheild had lost a nut. It was replaced and it sounds good.

 

Well I have the vibration issue now... My local service department is manned by Larry, Moe and Curly. Can anyone direct me to something can spell out to these stooges on how to fix my problem? thanks.

 

Bump... Anybody have any thougts on previous post?