Sub box behind seat - available space?

[ItWillBeSlow]

Currently planning out my audio components and have everything figured out except what sub I want to use..

I am going for a single 10" or single 8" sub, and would prefer a JL W3 (8W3V3 or 10W3V3 ideally). The 10" W3 requires 6" mounting depth according to JL, not counting the space in front of the box required to keep the cone from hitting the seat.

I cant find any actual dimensions of how much available space is behind a factory bench seat, pushed all the way back. I am planning a basic triangular box and can make it long if needed to get the volume. I don't know if this depth is an option or not. I want to build something similar to @SactoJim from this post: http://67-72chevytrucks.com/vboard/s...58&postcount=3

If anyone has dimensions from the back of a fully extended bench to the rear cab, please share. I cant get my set in for a while to check this myself. If you have any similar "basic" triangular single sub boxes behind your seat please share as well.

Thanks!