Upgrading...Maybe?

I would stay away from the CAT. I have a '06 and have spent a lot of money to get the hp/tq and mileage up to where the older CAT motors are. Also you know the truck you have under ya, that means a lot in my book.

 

Whats your fuel mileage???? Sounds like the conditions we drive over here fuel mileage is not at the top of my list of things to improve I would rather have a truck that I know and is strong enough to do the work.
I agree with pullingtrucker.

 

You have a non-aero truck with a strong but pig engine. I don't see how trading for another with different names will improve your mpg cause.

 

I would stay with the International. If it is doing you a good job and you know what you have I wouldn't make the change.

 

You know going from 411 to 370 will allow you to run the same speed at a lower rpm thus saving fuel but you will not have as much bottom end for starting out with those heavy loads so it will cause more wear and tear on other parts of your drivetrain such as the clutch.

 

Specing a truck with too fast of gears can hurt mileage as much as slow gears and such a heavy load.

What kind of mileage are you getting currently? Our T-8 w/ ISX500 only gets 5.3mpg with the 3.70 gears running long haul. My W9 w/ 525hp pre-ACERT C15/3.55 gears gets between 5.8-6mpg with the same loads. Haven't had a long haul with runnig the fuel temp mod yet, but currently getting a .4mpg/avg increase in mileage with it.