Ive been looking to add a aftermarket deck but i really dont want to have to buy a special harness for $100. GM Factory Integration Adapter General Motors Class II data bus interface — retains OnStar system, factory door chime, and Bose system with aftermarket radio at Crutchfield.com

Is there any other i can buy that might be cheaper.. i dont need to have the steering wheel controls or anything either if that helps.