Thanks! My dad and i built, and installed the whole stereo!
the box is 55.5 inches wide, 4.5 deep at the top, and 6.5 at the bottom. make it as tall as you can behind your seat, that one is 15 high, but i think you could squeak another half inch out of it. you loose a click on your seat, but is still comfortable. i am actually in the process of putting a seat out of a late 90's Chevy in it which takes up more space and would put me into the steering wheel too much, so a new box is needed, and if you buy the new kenwood xr-w12f you can build a box that is 2 inches at the top, and 7 at the bottom. im going to make the one for my truck 2.25 at the top just to get that little extra cubes in it,but you could make it work. here's a pic of a diagram i made with the real small box. with the small box the new style seat can be all the way back with the top touching the cab, so i imagine if you built that box for a old style seat it would be really comfortable, like there was no box there at all. its a little low on cu ft for the subs, but you these ol standard cabs either like you to be crammed forward, with lots of boom, or completely comfortable and have a little boom. ha i believe the 2-2.5inches at the top box is the perfect ammount, with a little relief cut in the back of the box the subs i have now, kenwood xw1200f's, will fit in the 2.5 inch top box. i just got to thinking, that 7 in. may not work on the bottom with the old seat. at 6.5 i can still get the seat all the way back, the seat back just wont stay with it, it flips forward, so that may be an option. pm me if you need more help.