First off, thanks for all the info provided by everybody in this thread!

I did receive a 2011 HHR Onstar module. Getting the panels off on the rear was the biggest pain in this whole thing. I just unplugged the old unit, plugged in the unit from the 2011 HHR and although the Onstar light turned red due to VIN mismatch, everything just worked.

The only question IO have is regarding the blue plug that has ridges that don't line up with the 2011 unit. Is this antenna connection just for Onstar? Since the Onstar service is defunct anyway, is there any point in hooking the antenna connection back on?

Thanks again everybody!!!

 

You only want BT, not OnStar. No need for OnStar antenna.
The 2011 plug might be different because it was equipped for XM/Sirius, also.

 

Thanks for the info!