I have a GMOS radio harness that i had in my 09 cobalt ss for sale. I had this in with my pioneer double din and it worked perfect. I believe this does work with onstar, but i did not get the extra harness to retain steering wheel controls.

Looking for $50 shipped and i will throw in a double din bracket for free, as well as the antenna adapter.

 

I'll take it. PM me your info and I can send money right away. I was just about to order a new one when this popped up lol.