yes you must buy a gmos-01 radio adapter
this is it here but u can search around for better pricing
Axxess GMOS-01 (gmos01) OnStar Interface for Non-Amplified GM
and for steering wheel controls you will need this
again search around for better price
PAC SWI-PSv1 (swipsv1) Pioneer and Sony Factory Steering Wheel
and you will also need the dash kit to hold the new aftermarket radio in
somthing like this
PONTIAC GM1596 Single din Radio Stereo Dash Install Kit | eBay
and u will also need a gm radio antenna adpater ( super cheap )
if you were buying the single din i would sugest that you go with a double din, but all the power to you, plus its free, hope all goes well hit this thread up if there are any more questions
