Under Toolbox Auxiliary Fuel Tanks

When you have a truck that’s already packed to the bed rails with equipment, it’s hard to find any extra space whatsoever for even a small auxiliary fuel tank.  If you find yourself in this situation, your best bet is to consider a small auxiliary fuel tank designed to fit underneath an existing truck toolbox.

Under tool box auxiliary fuel tanks are designed to maximize space and efficiency by keeping an extremely low height.  With a low height, these types of auxiliary tanks can squeeze underneath heavily packed pickup bed toolboxes.

Rectangular vs L Shaped Under Toolbox Fuel Tanks 

Rectangular under toolbox tanks are slim, light weight and very easy to fit directly underneath a toolbox.  The main drawback with these types of fuel tanks are they can only offer small to mid-sized amounts of fuel capacity.  

If you need extra fuel capacity, you might want to consider an L-shaped auxiliary fuel tank.  The L-shaped fuel tanks are sized so that the “lower L” portion of the tank fits underneath a crossover style toolbox. 

The big benefit of the L-shaped tanks is they can offer substantially larger fuel capacity than the smaller rectangular sizes.  The main thing you need to keep in mind with the L-shaped tanks is that you need to have adequate room to fit the larger back end of the tank inside your pickup bed. 

Measurements for a Rectangular Under Toolbox Tank

• Measure the space gap below your existing tool box to the pickup bed floor.
• The available space is the maximum height of your under toolbox fuel tank.
• Typically the available space under a truck toolbox tends to range from 9 inches to 13 inches.
• Don’t estimate the space, make sure to measure the exact gap between your toolbox and the bed floor.

Measurements for an L-shaped Under Toolbox Fuel Tank 

• Confirm the amount of space from the bottom of the toolbox to your bed floor.
  
• This space represents the maximum height the lower level L shaped fuel tank can be while still being able to slide underneath the available space below your tool box.
• Measure the width of the taller vertical side. This represents the additional space you need behind your toolbox to fit an L shaped tank.
• Another way to think about the side space is to picture a narrow rectangular tank sitting next to your toolbox. 

ATI Diesel Under Toolbox Auxiliary Fuel Tank

ATI offers two under toolbox tank options.  A smaller 30 gallon size with a 9 inch height and a larger 42 gallon size with a 12 inch height.

This tank is a light-weight aluminum tank with a diamond tread plate design.  The tank is DOT approved for diesel fuel.  The fill neck is designed to protrude from the side of the tank so you can fill up the tank without moving the tool box.

ATI’s tanks include an auxiliary fuel installation kit.  You just need to specify the make and model of your truck so we can provide the auxiliary fuel kit to match your vehicle.  

Aluminum Tank Industries auxiliary fuel tanks connect directly to the factory fuel tank. The auxiliary tank keeps your factory fuel tank full until the auxiliary fuel tank is empty. The fuel tank kit is easy to install with no wire splicing or switches needed. 

The tank includes rollover and vent protection, is fully baffled and includes a 1 year warranty. 

Available add on accessories include: 

• Tank Mounted Fuel Gauge
• Dashboard mounted fuel gauge
• Lockable fuel cap
• Black Powder Coat paint

Measurements (click gallon size to see the tank):

• 30 gallon: 9 inches high x 48.5 inches long x 19 inches wide
• 42 gallon: 12 inches high x 48.5 inches long x 19 inches wide

ATTA Diesel Auxiliary Under Toolbox Tank

ATTA offers two sizes of under toolbox auxiliary tanks.  The smaller size (30 gallon) option is designed to fit short bed pickup trucks with an over the bed rail style toolbox.  The lower portion of the tank is notched which reduces the bottom tank length and allows you to fit the tank in between the wheel wells of a short bed pickup. 

The fuel tank comes with a single driver’s side fuel fill neck which is located on the side of the tank for easy access. 

ATTA auxiliary tanks are required to use ATTA’s proprietary fuel system.  Choose the automatic Freedom Fill System or the more manual Push N Fuel system.  We recommend the Freedom Fill System because it has a built in program that prevents overfilling your fuel tank. 

This tank is designed to fit: 

• Short Bed Ford, Dodge and GM diesel trucks.
• The tank may interfere with the factory puck system on Dodge short beds.

Measurements (click gallon size to see the tank)

• 30 gallon*: 9 inches high x 54 inches notched length x 21 inches wide 
• 38 Gallon: 9 inches high x 60 inches long x 21 inches wide

*Top tank length is 60 inches and bottom notched length is 54 inches. 

ATI L-Shaped Diesel Auxiliary Under Toolbox Tank

ATI’s L-shaped Aux tank provides flexibility to fit underneath a toolbox while also offering a significant boost in fuel capacity to 80 gallons.  The lower L height is just 9.5 inches so you can easily slide this tank underneath most crossover style toolboxes. 

This diesel auxiliary fuel tank also includes ATI’s fuel installation kit. 

Measurements:

• 80 gallon: 26 inches high x 48.5 inches long x 28 inches wide

• Low L Height (A) - 9.5 inches
• Low L Width (G) - 20 inches
• High L Height (D) - 26 inches
• High L Width (E) - 8 inches

Fuelbox L-Shaped Diesel Auxiliary Under Toolbox Tank

With the Fuelbox L Shaped diesel tank you can fit this underneath a tonneau cover or you can slide the lower L side of the tank underneath a toolbox or other equipment.  This L shaped tank offers just 8 inches of height on the lower "L" level which makes it extremely easy to fit underneath extremely tight spaces.

You have your choice of two sizes: a smaller 55 gallon option and a larger 70 gallon option.

Keep in mind the fill cap adds an extra two inches of height to the tank. 

Measurements: 

• 55 gallon: 19 inches high x 53 inches long x 23.625 inches wide
• 70 gallon: 19 inches high x 53 inches long x 28 inches wide

L Shape 55 Gallon Measurements:

• Low L Height (D) - 8 inches
• Low L Width (E) - 14.625 inches
• High L Height (A) - 19 inches
• High L Width (G) - 9 inches

L Shape 70 Gallon Measurements:

• Low L Height (D) - 8 inches
• Low L Width (E) - 17 inches
• High L Height (A) - 19 inches
• High L Width (G) - 11 inches

Browse all Under Toolbox fuel tanks below or see other auxiliary fuel tanks for sale.