Ok, Im gunna be posting my progress and results on this new thread, for a custom 10" sub box Im currently making that will fit under the rear drivers side seat and extends under the center rear seat.
Here is a link to the Speaker-RCA Level hook up: http://chevyavalanchefanclub.com/cafcna/index.php/topic,115804.msg1804069.html#msg1804069
My Goal: Have a custom 10" Sub Box with proper cuft volume for the speaker and allows the rear seats to fold down far enough to allow the midgate to function at least 95% of the way down.
I didnt want to Hijack JEFF D's 8" Sub thread, since Ive now decided to try the 10" box. Ive been posting a lot on JEFF D's thread because I was going to do the 8" boxes, but Ive decided to try a complex 10" box design, and test the sound. If it doesnt work, Im doing the Dual 8's - I will be out $30 in supplies - no biggie. (and 30 hours of time!!) haha
The other under-the-rear-seat boxes that are sold dont allow the midgate to fold down anywhere near full-way, but I think I will get mine to fold down all but 1"...to me, that 1" is insignificant because when I put something heavy on the gate, the seats can compress 1" without ruining them.
Attached is a picture of the bottom of my enclosure, I will be building the sides and top over the next week or so, and I will post pics of it, and the final box installed with the seats down and mid-gate down.