Transfer Flow 40 Gallon Diesel Auxiliary Tank System 1
Transfer Flow 40 Gallon Diesel Auxiliary Tank System 2Transfer Flow 40 Gallon Diesel Auxiliary Tank System 3Transfer Flow 40 Gallon Diesel Auxiliary Tank System 4Transfer Flow 40 Gallon Diesel Auxiliary Tank System 5

Transfer Flow 40 Gallon Diesel Auxiliary Tank System 6Transfer Flow 40 Gallon Diesel Auxiliary Tank System 7Transfer Flow 40 Gallon Diesel Auxiliary Tank System 8
Add Fuel Level LCD Screen?:

Add Lockable Tank Cap?:

Lead Time:  1-3 Days
Ships From: California


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Model: TF-0800116637
Manufacturer: Transfer Flow

This is the Transfer Flow 40 Gallon Diesel Auxiliary Tank System. Finally, an almost universal auxiliary fuel tank. Our 40-gallon in-bed auxiliary fuel tank system is designed to be compatible with almost any diesel truck, including half-ton pickups, trucks with utility beds, RamBox equipped trucks, or those with a factory installed 5th wheel prep package or other 5th wheel hitch. The patented fuel tank design has a recessed cover box where the sending unit, rollover valve, and fuel filter come preassembled. You'll be pleased that its low height means it can fit under most standard tonneau bed covers.

This auxiliary system is computer-controlled by our patented TRAX 4 operating system with exclusive AutoTrans technology. Computer-controlled automatic fuel transfers mean worry-free operation, and much safer and more reliable operations than gravity fed systems.

Want to know the status of your on-board fuel systems? Simply download the TRAX 4 app to your smart phone and enter your vehicle and fuel system information. In no time, you'll be able to monitor your pickup's fuel capacity! During fuel transfer, the message "PUMP ON" will be displayed. You also have the option of displaying either the gallons or the percentage of fuel in each tank.

If you prefer not to use our TRAX 4 app with your auxiliary tank but still want to know how much fuel you have, Transfer Flow offers an in-cab fuel level monitor LCD. The LCD shows the fuel level of the auxiliary tank with an easy-to-read bar graph that decreases when fuel is transferred to the pickup's main fuel tank. This item is sold separately.

Built from ReliaSteel, high-yield U.S. aluminized steel; and powder coated black, TFI tank systems offer superior corrosion resistance and strength.


  • Recommended for drivers who require additional fuel capacity but require a small footprint to maximize available bed space for 5th wheel hitches, Rambox beds, and cargo
  • Won't interfere with standard 5th wheel hitch
  • Fits under most tonneau bed covers
  • Robot-welded seams provide extraordinary strength, unlike rotationally molded plastic tanks or cheaper steel brands
  • Our fuel tank systems include all components needed for installation
  • TRAX 4 computer-controlled automatic fuel transfers for worry-free operation with exclusive AutoTrans technology
  • Built from ReliaSteel, high-yield U.S. aluminized steel powder coated black for superior durability and strength
  • Baffled to prevent fuel sloshing
  • 6 year, unlimited mile warranty
  • Made in the USA
  • If you want to get your hands dirty, you can easily install the fuel tank yourself. Our tank systems come with comprehensive step-by-step instructions to make installation a breeze. We also have installation videos on our YouTube channel to walk you through each step of the process.

Fuel Type: Diesel
Dimensions: 48"L x 19"W x 19.38"H
Fits: 1999-Current Dodge Ram, 1999-Current Ford, 2001-Current GM/Chevy
NOTE: Product dimensions include 1 1/2" in width for the mounting brackets and 3" in height for the filler neck.

NOTE: If you have a 2010-2012 RAM Mega Cab Short Bed - an additional Filler Neck Tee Kit is required for $179.39
If you have a 2001-2004 GM Pickup - an additional Filler Neck is required for $74.95

If you need these parts, please call us and we can add them to your order.

User Guides & Manuals

PDF  TRAX-4 Users Guide

PDF  TRAX-4 Installation Manual

Optional Accessories

  • Locking Vent Cap: Keep your fuel safe and secure with a locking gas cap. Comes with two keys. Includes a tether to keep the cap connected to the tank

Transfer Flow
Transfer Flow Warranty Details:

Transfer Flow fuel systems and parts are covered by a Six (6) year unlimited mile warranty against defects in material and workmanship throughout the U.S. and Canada from the unit purchase date by the original purchaser for the original vehicle the unit was installed in.

Warranty will not apply when product failure is caused by conditions beyond the control of Transfer Flow, such as:
  • Malfunction due to incorrectly ordered product
  • Damage from misuse, negligence, or failure to provide reasonable and necessary maintenance
  • Damage caused by improper installation
  • Damaged caused in shipment or improper handling
  • Damage caused by contaminated fuels or fuel additives
  • Product modification or alteration
  • Products made from pickled and oil material are not covered under warranty for corrosion
Any action against Transfer Flow for breach of the warranty must be commenced within one (1) year after the cause of action has accrued.

Any action against Transfer Flow for breach of the warranty must be commenced in the Superior Court of Butte County, State of California.

For specific information regarding part exceptions, exclusions and limitations, warranty claim procedures, and federal regulatory provisions, please read our full warranty details on our warranty page.

Inc 5000 Award
Inc 5000 - Award has been awarded a ranking of 1565 out of 5000 of the fastest growing private companies in America!