It sounds like Zep and is probably meant to though that type of bloated 12-bar stuff leaves me cold, never having really liked Zep and their use of chords and harmonies that tend to be neither here nor there as regards minor or major key (I know, that is part of their charm, I do respect their contribution to rock music, it just doesn't sound "right" to me though).
This is actually one of the worst songs on the new Petty album. It's overall a very guitarish album (even back in the eighties Tom phantasized about doing "an all-out hard rock album", this is not quite it, but it goes in that direction). And Led Zep isn't the only band that gets a nod, so does Wishbone Ash, twin harmony guitars and all, someone must have given Tom and Mike Campbell a copy of Argus:
http://www.youtube.com/watch?v=n0JwsooTM6M&feature=related
