okay well take down the max dimensions then we can help you out with a box design.

 

The max external dimensions are as follows: 49" width by 19" height by depth unknown, as its a truck and depth isnt a concern. Although i would like to keep it to 2 seperate enclosures if possible, thanks.

 

You want two separate enclosures to make it easier to put in? You should basically split it in two down the middle, so two 24x19 boxes beside eachother someone said 2 cubes per sub so that's about 16 inches deep to get 8 cubes total sealed, if you wanna go ported youll have to decide what style of port and what size then adjust the length of the box to add volume to compensate for the volume lost to the port

 

ok, so using Winisd, i have come up with these calculations:
using 2 12"s in a 3.5 cuft enclosure with a port that is 20sqin by 9in long, giving me a 34.76 tune. What are your thoughts on this! Keep in mind the music i listen to on a daily basis. What whould you change?