new help with box for 4 8s r 2 10s

[1stock04]

ok i have a single cab 84chevy truck i wanna either do 4 8s or 2 10s behind tha seat. heres tha measuresments. also what tha air space of this box so i can get tha right subs. this box is built strickly for spl. o also what tha formula to find tha air space for any box.

http://img406.imageshack.us/i/66036732.jpg/

[Guest]

with those measurements, i got 2.03cuft with a sealed box, no drivers, using .75" MDF.

[1stock04]

with those measurements, i got 2.03cuft with a sealed box, no drivers, using .75" MDF.

can u tell me how u got tha.