I have an iphone 5 and want to play it in my 1997 GMC Jimmy?

I don't have a USB in my car. However I do have a thing that worked for my iphone 4 that plugged into a car lighter and then into the aux port of the phone and it played find. It won't play through my iphone 5 though. Is there any other way to play music from my iphone 5 to my car stereo?

Replace the head unit with a new stereo that has the correct connector port for your phone.