I own an 01' crew cab and was wondering what was under my backseats? There is just a carpeted piece right underneath it at the very front, and it sounds pretty hollow when you hit/thump it. So I was thinking if it was hallow I could cut it and do an under the seat sub setup like all the 2nd gen frontiers do.
Sheet metal floor pan with the gas tank on one side... Im planning on doing the same some day and that was part of my motivation for a bodylift. There really isn't much room down there.
I've considered making sort of a shallow box/platform that I could swap out with the back seats. Then I could throw all kinda stuff back there (like I already do) without worrying about the seats.