gas tank under a ''6"

I've got plenty of body work to do yet on my 56 cj6, so I've got time to think about this. My thoughts are fabricating a tank for the "6" area underneath, between the body and frame. I would like to keep the tank under the seat for extra capacity. the filler neck can go just behind the original. I think I could get 5" high x 16" wide x36" long without any problems, and no other mods. What would be the disadvantages to this way of thinking? all thoughts are welcome

 

That option has been looked at many times before...............really depends on what your building it for and the drive train and type of suspension that your planning.
The body structure is probably not strong enough to support a large tank which could be as much as 30+ gallons , so more than likely any tank would have to be frame mounted and the cavity or space above would be just a blind opening........frame mounted and a body floating on separate mounts will cut down on the available space to allow for flex , notwithstanding you have a drive shaft that goes right through the middle of that area.............perhaps a pair of saddle tanks or one on each side of the drive shaft may work..........but if your looking to keep the underside of your Jeep High and clean that does not leave you allot of room between the bottom of the tank and the frame..........if your only thinking a small tank that's another option.

Not to say it's a bad Idea, just not sure that the benefits are great enough, lots of guys have converted that area to storage.......which may better suit that area.

 

If you decide to go with a custom sized tank, try Boyd Welding in FL. I had them make one for me and they were reasonable and beautiful welding. All aluminum.

 

You can have two under seat tanks and the rear tank, which gives you 11 + 11 + 15 = 37 gal capacity. IIRC MTS sells a plastic right-side tank, or you could move the neck the opposite side on a steel tank. This has been done many times. When you add the second under-seat tank, you lose the tool box. This could be made up with quite a lot of under-floor storage in the area you are describing. Building storage should be simpler than building a fuel tank. I would also consider putting a water storage tank in that area.