diff. gears

[timowen1]

I have a 2003 GMC 2500 HD 8.1 Allison 4x4. The truck was not ordered but purchased from in stock. It came with 3.73 gears. I pull about 10,000 lbs through out the spring, summer and some of the fall. ( car and enclosed trailer) The trailer does create a good amount of wind resistance. The truck pulls as if it has nothing behind it most of the time, but when I pull through the mountains or foothills it does seem to strain. Sometimes what seems to be more than it should. Would changing the differentials gears to the 4.10 that was available help? Would it be significant enough to offset the cost of the parts and labor and decreased fuel economy? When running empty at 70 mph I am running about 2000 rpm give or take a little. Fuel economy on the highway at this speed on a trip is about 14 mpg. It would make sence to me if the motor is not working as hard to pull with lower gears it would not use as much fuel even though it will be running slightly higher rpm.

Am I dreaming???

Tim