I am big on car audio, I just built a custom ported box with a 12, two 10s a bass EQ and amp on it, the thing kicks hard, its in my car right now.
I had a ford ranger, and my set up in it was a single 12 sony xplod with a 600 watt RMS (forget the peak power, RMS is what counts) Power Acoustik amp, and, it sounded like crap, because trucks are hard to make thump good, I had an alpine deck in the truck with 3 way component speakers in the rear (6x9's) and 6.5 inch 3 ways in the front doors.
On that truck, you should be able to remove the door panel, then the peice of metal the speaker bolts on to should be removable, if it is, remove it, and you have like a 8 inch hole there, grab a peice of MDF (about 14 inch or a little more) cut it retangular, and cut out a 6.5 inch hole, or go 6x9's if you can make them fit. Dont hack away at the door frame, because it will take away the structural integrity of the door, and no matter what anyone says, your life is worth more then havin yor truck sound cool.
Curtis
Currently Trikeless- but I have a LT250R