Well, i have an ext. cab truck.....box is bolted with 8 bolts to the floor...rear seat pads are obviously removed. Shit won't go anywhere. Check out aurorarav8's gallery...pretty good way to secure box. peace
first make sure that the gas tank or nothing else that can be harmed is beneath the subs, then the best way would be to drill a hole about 14 mm wide through the box and floor of the trunk, then have a buddy slide a bolt through the hole, go under the car and tighten a nut onto the bolt. the box will go nowhere
I have an extended cab truck as well and actually had a bracket welded that fits into where the seats used to bolt down at. It's nice because they are BIG bolts and I don't have to drill through anything!!
When you've got a 70 pound sub in your box there's no need for it to be mounted. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
I did use some L brackets though, cheap and effective.