[capev86]

Beauford: that gas mileage is good considering the 4.10 rear. a 3.73 would get you about 18 but with the heavy trailer the slightly steeper gear makes it easier on the truck using overdrive.

it is not a question so much on how much power you put through it but more on condition of the equipment, quality of fluids you are running (synthetics are a good idea), and how you drive that influences lifespan of your transmission. that trans could easily live behind a 1,000 ft-lbs of torque in the right conditions provided you apply the gas smoothly like you should be when trailer towing. stomping on the gas is a quick way to wear out equipment.