[hankaye]

Cyncwby, Howdy;

Like the others I don't have the model that you are looking for/at ...
That said, I do have a '04 F-250 (different engine), and it has a different
transmission, it does have the 3:73 rear and my tires are not the stock
from the factory size (slightly larger diameter and width).
My experience is that I sometimes get 18.something mpg while NOT towing.
Usually, 16.5 -17.5. While towing I get 10.5 - 11.5. That is from Grants, N.M.
to Green River, Ut. as an example.
I attempt to keep my rpm's at or slightly below 2,000 rpm, what some refer
to as the "Power band" area. That translates (for me), as roughly 68 to 73
mph. For me, ... 1500 rpm translates to roughly 55 mph.

Good luck with your new truck! Let us know how it works for you.

hankaye