Not to revive an 8 year old thread -- but here's something I threw together for my 7.3L starting batteries -- I wanted dual Group 31 AGMs...
Still deciding if I should do this or just go with the Group 65....
I dig using the terminal bulkheads for safety. Easy to access to disconnect the batteries safely that way.
I'm not even sure the fab shop I work with can bend a box with these dimensions with their press brake tooling. I'll have to ask them as it'll definitely involve gooseneck tooling.