I got a 2005 chev equinox ls and I want to replace the factory stereo so I figured it would be simply buying an interface and dash kit and stereo anyway I bought a LC-GMRC-01 interface but it doesn't work was told it would.Now my question is what interface would I need I'm not sure if I need one with onstar and factory amp etc I was told factory amp was under the back seat but theres none there and I don't see onstar anywhere sorry didn't have the SUV long and always owned Hondas.Any help would be greatly appreciated