Looking for a popular/alternate version of Tom Petty's 'American Girl'. Does anyone know it?

I've heard it a number of times on the radio. It is Tom Petty, but the instrumentation is different in this version. It's smoother, more of a band/acoustic sound to it. A little more country. I think there are even some backing vocals/harmonies, but I can't remember though. Sounds like an all round, polished version of the song. If I didn't already know the original, I would have thought that it was the official version...