Considering Diesel A - 275 hp Cummins questions?

I have the same engine, but rated at 260 hp, a 2001 Cummins. 36' Expedition. I have nearly 80,000 miles and tow a Suzuki Grand Viagra, 3100 lbs. 47 of the 48 states and overall fuel mileage of 9.22 mpg. We full time and it gets regular care and feeding. I'm not the first to the top of the hill, but I'm the last one at the fuel pump. Its really very adequate for the task. Sweet spot for travel is 62 mph. It will easily cruise at 70 if I'm in a hurry.