i had a 94 silverado, i ran a 8in bazooka bass tube under each seat in the rear. it had a perfect place for them, ran the amp under the passenger seat and the 10 disc kenwood changer under the driver seat. it was super bass loud from a small package. i sounded great and was easy, and pretty inexpensive compared to subs and a box etc. the beauty of a bass tube also is that you dont need a box to get that air trapped.
the only thing is i dont know if you still have the same clearence under your seats as was in the 94 body.