Fix or change out

Is the truck in decent shape? Late 80's early 90's 454's or really popular with the performance crowd, you could sell it and move on to something newer and more efficient. Otherwise, give it a good tune up and thoroughly clean throttle body and all filters and sensors. If you have big knobby tires, those kill gas mileage. You can also look at a tranny or rear end swap for better gearing/OD.

Those trucks are known for really poor fuel economy. I am guessing you are averaging less than 10 mpg which is fairly normal. You could install a higher gear ratio differential or a small block engine but that is about all you can do to improve fuel economy other than a tune up.

It's like a Triton V10, if you have to ask what the fuel economy is for it, you can't afford it.

I suppose that is true Ken but the 454 dually 1 tons are much worse.