what kind of music do you listen to?
another sub that you can consider is the Elemental Designs 7kV2 @ edesignaudio.com
it's a 6.5" small box sub (0.25-0.5 cu ft), so you can fit a wedge box behind your seat (towards the bottom), while the top of your seat reclines against the cab
the thing that works to your advantage is that you've got an '04...it has ghastly more space than the 89-92:
with my tools:
amp, and space for sub: