My own personal '54 Panel(actually, my wife's)has some sort of car gas tank mounted under the back of the truck with the filler exiting right in the center below the doors. Eventually we'll be going back to the stock tank, but other issues take precidence over that right now.
On the customer's pickup, I believe he didn't want to use the across the rear tank because he wanted to retain the spare tire mounting(Justin, if you're reading, feel free to chime in).
Brother's has a tank with a top exit in the left rear corner. Looks like we can come up through the bottom of the bed and angle it through the bedside behind the fender. We'll have to fabricate a cover plate to dress up the tube where it runs through the bed. Not the ideal solution because there goes the spare tire location, but I'm not crazy about notching the frame for the panel truck filler neck either.
