I just started designing a box for my s10, i have a lot of measurements down and ideas drawn up. I am planning to build a box that will cover the lower half of the back wall in my extended cab s10, its gonna hold 2 12" subs and my amp. the only problem is I dont know how i should anchor it down, so it doesnt move or come off the back wall. I wanna keep it right against the backwall to save space and so i can keep my 3rd seat. How do you think i should go about anchoring it down?