[408F150]

The engine is near bullet proof so you don't have to worry about that. The weak point in towing is going to be ATF temp, which will start to hit 200*+ after a few miles of a 6-7% grade. A large transmission cooler and a deeper pan (along with high grade synthetic ATF) kept my transmission under 210* going over the grapevine with a 7k toy hauler; and that mountain is as long and steep as I've ever come across. Any pass big enough for multiple run-away truck ramps I think is a good test for a transmission cooling system. If you really want to make it easier on your truck drop in some 4.10s, I went to 4.56s with my 35" tires (which is similar to a 4.10 on stock-sized tires) and only lost around 1 mpg highway but gained better towing milage and much more power charging up the hills.