I have a 454 GMC (2500 CC) and a 6.0 liter Chevy (2500HD std cab), the 454 is a thirsty puller, but reliable. The 6.0 is rated at the same HP, lower torque, but pulls trailer really well. I know a buddys 5.9 magnum is no hotrod, and he is always looking for power, and filling it (2500 4x4 SC). The 10 cylinder Ford OTOH has a rep for good pulling and good on gas, know 2 guys with those. The guys I know with 5.4's like them, they are not stellar pullers, and a GM 6.0 will outpull them, but they are reliable and decent on gas. I have heard that the 10 cylinder is about as good on gas as the 5.4-8 cyl though... In the bunch I think the transmission is the weak link, and the GM 4L80E is about as good as it gets in 3/4 ton transmissions.