The Jeep is notorious for limited storage space.  Several of my upgrades and custom projects involved ways to increase or optimize any available storage space.  I've always had a thing for military surplus equipment.  One reason is military anything usually means heavy duty and durable.  It can also mean plentiful and cheap as in the case of ammo boxes.  You can usually find ammo boxes anywhere from army surplus stores to flea markets to garage sales to tool catalogs.  They come in all kinds of sizes and various shapes.  Many ammo boxes are also water resistant.  My garage has many of them containing tools, chains, tow equipment and some with just junk in them.  So when it came to adding more storage space to my Jeep, it just made sense to find a place to mount a few ammo boxes.

When I set out to mount up the ammo boxes I first determined where to mount them.  I decided on mounting three Ammo Boxes over the rear fender wells.  Two were to contain tools, and the third would contain the essentials for a First Aid Kit.

I wanted the Ammo Boxes to be as easy to access as possible and also to have the ability to remove them quickly if necessary.  They also had to be mounted strong enough to withstand the abusive jarring that the Jeep will experience offroad, even when the ammo boxes are fully loaded with heavy tools.  The last thing you want to worry about is 20 pounds of tools in a steel box whacking you in the head.

So with that in mind I set out to design a mounting bracket that would allow quick disconnect and yet be strong.  I debated over all types of fasteners and clamps available on the market. Most I simply didn't trust would hold.  I also didn't want to spend a lot of money.  What I came up with was the following, very simply idea that would cost you no more than the price of a few bolts and maybe for a piece of angled steel if you don't have a free source for metal scrap.

For my simple mounting brackets I used some scrap I acquired from a local steel shop's scrap dumpster. That's a great tip by the way.  Talk to a local steel shop and ask them if they have a scrap dumpster and if they would mind if you could get a few scrap pieces for a project.  The scrap is usually recycled for pennies on the dollar for what it cost them in raw material.  Buddy up to the guys and you might make a friend.

The brackets were 16 gauge galvanized steel 90° angles approximately 1½" x 1½".  I cut them down to about 4 inches for the larger ammo boxes and 3 inches for the smaller ammo box.
There are two angles per ammo box.  One angle get bolted to the Jeep fender well at the hinge side (rear) of the ammo box and the other gets bolted to the ammo box itself on the latch side (front). The latch side, pictured to the right, is bolted about ½" up from the bottom using 2 - ¼" grade 8 bolts.  The reason for bolting it about  ½" up is to make room for the nut that hold the 7/16" bolt that comes up through the fender well.  As you can see in the picture, I rounded the angle so there we're any sharp edges.
The rear bracket is bolted down to the fender well using two 3/8" bolts.  Two ¼" grade 8 bolts go though the ammo box with about 3/4" of threads sticking out past the nut that holds the bolt on the ammo box. The reason for allowing the bolt to stick out of the box is because the bolts will go though the bracket.  Typically I don't have any nuts on the very end of these bolts because without nuts, I can un-wind the wing nut on the front of the box and lift the ammo box out of the Jeep.  Currently I only have the First Aid box without the rear nuts while the Tool Ammo Boxes have end nuts.  This is for safety reasons in case the wing nut works loose. Three bolts come up through the Jeep tub's wheel well.  Two 7/16" or 3/8" grade 8 bolts for the rear of the box and one 7/16" for the front of the box.  These three bolts go up through the brackets.  The rear of the box is bolted down to the wheel well.  The front has a wing nut for quick disconnect.
This method of securing down the ammo boxes was pretty easy to do and works great.  It's a minimal bracket and allows for easy access to the ammo boxes when I need them.  Not to mention it's cheap to do, requiring only a few parts, all of which I had lying around.
There are plenty of different sizes and types of ammo boxes including rock launcher boxes.  All of these types of army, military surplus make great storage boxes.  With a simple method for mounting them and keeping them secured down for the rough ride, they've become invaluable for storing my tools and spare parts, not to mention my First Aid kit, something all offroad vehicles should carry.