Do you love your truck but wish you could drive longer between gas ups? A few companies make aftermarket fuel tanks that hold up to twice the amount of fuel as your truck’s stock tank. These tanks are shaped a little differently than the original equipment manufacturer’s (OEM) tank, but fit into the same space on the undercarriage of your vehicle.
In this article, we’ll take a look at the undercarriage tanks made by Transfer Flow. Transfer Flow makes replacement fuel tanks for select Ford, GM, Dodge, and Toyota trucks.
Benefits of a Replacement Fuel Tank
Changing out your truck’s stock fuel tank for a larger replacement tank will give you a much longer driving range while preserving precious bed storage space.
While Transfer Flow also makes in-bed auxiliary tanks, you’re going to have to sacrifice storage space to use them. If you tow a fifth wheel trailer, an in-bed tank probably isn’t even an option.
Transfer Flow’s in-chassis replacement tanks are made from 12 and 14 gauge aluminized steel. The company says that replacing your existing tank with one of their larger ones won’t void your vehicle’s existing warranty, and the new tank will hold up just as well as the original would.
Example of the size and shape differences between a stock fuel tank and a replacement fuel tank.

Transfer Flow
If you’re interested in replacing the fuel tank in your truck, the first thing you need to do is select the correct tank for your vehicle. Transfer Flow makes replacement tanks for most major truck models, including Dodge, Ford, GM, and Toyota.
Using their search feature, input the specifics about your vehicle.
You’re going to need the following information for your truck:
- make
- year
- model
- fuel type (gas or diesel)
- chassis
- differential (2WD or 4WD?)
- axle (dually or standard)
- cab type (extended, standard, or short)
- OEM tank (is your existing tank positioned aft or midship?)
Here’s what the search form looks like when filled in.
Replacement Fuel Tank Installation Specifics
Transfer Flow has over 300 authorized installers located in the United States and Canada that can do the swap out for you. Their tanks are engineered so that you can use existing gas and diesel fuel lines, and you won’t have to move your spare tire or lose any ground clearance. The tank fits snug inside the chassis frame.
Each replacement tanks is baffled so you won’t hear any more fuel sloshing sounds than you normally would with your stock tank.
Example of a 45 gallon replacement fuel tank kit for a GM truck.

Transfer Flow
This is the 58 gallon kit for a Dodge truck.

Transfer Flow
Transfer Flow’s fuel tanks have a black powder coated finish. You can also choose a top-of-the-line polymer finish for added durability. This finish is the same stuff that they use to spray on bed liners, and costs an additional $150.
Example install of a Transfer Flow replacement fuel tank on a Ford truck.
Original video by Transfer Flow
What do you think about upgrading your stock fuel capacity? How would the increased driving range benefit your travel?
Source: Transfer Flow
Some replacement fuel tank manufacturers and retailers:
- Transfer Flow
- Titan Fuel Tanks
- JC Whitney (search for ‘fuel tank’)
- 4 Wheel Parts
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