Be very careful.I'm not sure if they make a kit yet for the aftermarket radio.
The Radio in your car is actually considered a module.All of the modules(door switches,brake module,ecm,body control module,etc) have to talk to each other.If one doesn't communicate then,you will have communication errors and possible warning lamps.
You may consider upgrading your radio for a different GM radio as long as your RPO codes will allow the change.You can consult your GM dealer for upgrading radio options-then it will need to be programmed by the dealer.
It's not like the old days when you can just swap things out-unfortunatley.