I have bully dogs in my Diesel's. My friend bought this one for his 360 gas. He is running a tank through so we can get the mileage. I will post it . His was 11mpg at best.
My one Diesel 05 single gets as high as 24 towing. My 05 dually 14-15 towing same drive lines the only difference is the fenders , extra wheels, and no cap.
When I fill the dually up the distance to empty is 380-400 The single is always 600 or better, both trucks are on performance chips. same gears both 6 spds. Go figure