I replaced the OEM tank on my '13 F350 with a Transfer Flow 50 gallon replacement tank. In installed it myself, and it is one heavy duty beast. It's built rock solid and took me about five hours to install. Once it was installed, I took it to the Ford dealer and had the truck reprogrammed for the 50 gallon size. The fuel gauge and distance to empty numbers appear to be right on.
I love the fact that we can tow our FW over 500 miles before we have to fuel up, and that my bed is not cluttered with an in-bed auxiliary tank. After we tow all day, we like to drop the FW off at camp, and head into town for diesel fuel. It's just so much easier maneuvering without the FW behind us.
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The tank on the right is the original Ford Tank and the one on the left is the Transfer Flow replacement tank.
If you purchase on-line, try using coupon code FB75 for $75 off on a replacement tank. If that doesn't work, TF50 for $50 off.
Jim