My answer stays what my last post said. I guess I'm the "Someone told me to send the sticker inside the glove compartment, " Read the post just before your necro post.

In your case the UE1 means the car has Onstar, which accounts for the sharkfin (not the same one for XM).

As far as I know the headunit is the same the XM interfaces via the BCM.

 

That’s what I thought it would be. I have a separate antenna at the front for the radio as well. Are the hookups the same on all the different radios?

 

Yes, but note the DK GRN wires are computer LAN connections. The HU already has that wire.

 

There are only 2 radio HU , one with single CD the other with multiple CD capacity.
the OnStar , Pioneer, Bluetooth features are added on and controlled thru the BCM interface