Here are more pics of the cargo box from when it was in the 4Runner.
http://www.pnw4runners.com/index.php?dir=cargobox/
You can see the impact wrech too, and the old Powertank in a few of the photos.
A few months back I bought another Powertank, and here it is next to the box.
http://www.pnw4runners.com/temp/back_in_black.jpg
There is not as much room in the FJ, as I also use to have a 15" JL W6 subwoofer in a sealed box behind the cargo box.
The Powertank will not fit beside it, so I am thinking of drilling holes in the top of the cargo box and bolting down the PT bracket to it to hold the PT.