Coupe,
Even my 1-ton dually with the 488 V10 downshifts going up a hill with the trailer and two horses -- Like Tony said, that's what the tranny is for. A buddy of mine who pulls a lot of hills told me that when the truck lugs down (he has a 3/4-ton with a utility body that he hauls a Bobcat with) really far and struggles, he shifts into 4WD. He claims that transferring the power from one axle to both helps spread the stress and makes it easier on the truck.
My truck has never been challeneged that much so I've never tried that myself, but it does make sense.
Just a thought...
Regards,
John
