Water Pump (4 Times, but my own fault)
Engine oil seal (again, most likely my own fault due to problem above)
I see a lot of people complaining about losing the fuel pumps in the dual fuel tank models. This is a common problem since the operator (this means you) actually has to switch tanks when one is low. If you fail to do this, or run the tank until the engine begins to stall, then there is little or no fuel in the tank to cool the pumps, and they will eventually burn out. There are very few pumps (water, fuel, etc) that are designed to run dry. And those that are, are generally less efficient.
My only advice is to switch tanks when the needle goes to empty, don't try to push it.
Just wondering, what kind of fuel mileage does your truck get?