No one of those numbers correlates to anything useful. You need to find something called Brake Specific Fuel Consumption or BSFC. In the real world it's going to be too complicated to calculate the actual cost without a road test but you can compare BSFC to compare the cost of operating each engine.

A BSFC curve gives you power vs fuel consumption, you then need to make some assumptions for power needed to move the vehicle based on weight, aero, and drive cycle. As mentioned, inputs vary quite a lot so its usually best to simply make a guesstimate based on the advertised EPA fuel economy numbers for the specific vehicle.

If the drive in question involves carrying a 1 ton load, it's probably in a >8500 lb GVWR vehicle, for which EPA estimates aren't provided. But, it's not hard to find real-world experience for specific vehicles.

We don't really know what the original poster wants to do. "I am trying to determine the cost of commute to drive to a feed mill for bulk (1 ton) chicken feed." - (1) Huh? (2) So what? (3) Are you trying to make a comparison between different vehicles, or justifying the cost of doing it at all, or something else, or what's the situation?

A truck that's bigger and heavier than it needs to be, will cost you. Use the right tool for the job.

A diesel engine will usually use less fuel than a gasoline engine. But, it may cost more to maintain.

An old-school torque-converter 3-speed automatic is a fuel-economy killer compared to a modern 8- or 10-speed automatic, many of which do better than manual transmissions (because they can be better at picking the right gear for the situation than most drivers are - the control algorithms are far more advanced nowadays than they were 20 years ago).

A modern downsized but heavily turbocharged gasoline engine might achieve spectacular EPA ratings when driven lightly loaded, but be thirstier when heavily loaded than a larger-displacement but more mildly-tuned engine. There's sound reasoning behind Ford's choice to develop a 7.3 litre naturally-aspirated V8 gasoline engine for their medium-duty trucks, as opposed to throwing an Ecoboost in there.

Number one recommendation if fuel consumption matters ... drive slower. Within reason, of course.