I would also go with a set of 8's you should even have enough room to port them and it will play much MUCH lower than a 12 in a sealed box with that little air volume and that close to you

the RE8's or Image Dynamics ID8's both work really awsome for under seat boxes

 

If you are talking about a newer f150 crew cab (4dr) we just finished one with the sws 12 from Earthquake and it worked sweet.
PM me for more info.

 

^thats the sub Id go with [img]graemlins/headbang.gif[/img]

 

well im talking about a 2004-05 f150, with the extened cab, not 4 full doors but 2 full and 2 half doors,

i appreciate all the info guys, anymore ideas?

 

by the way i carry 4 to 5 people in my truck daily. so the rear seats are kinda important. thanks again for all the help

 

do somethin like this not as big as this on. I know that one of the seats in the back folds forward. so put the box on top of it and then fasten it to the truck. I had that box in my 98 f150 for along time with nothing wrong. Just I want some more bass. Just a thought.

 

Something else to consider....
http://www.mtx.com/caraudio/products...0C04_Specs.pdf
All of the Thunderform enclosures that I have ordered in have been above average for tonal response, fit and finish. It is a sub, box, amp and wiring kit all in one package. I think it would fit the need for most people just fine.