[kaisen]

The 6.0 is a very solid motor. I have a 2006 with 233K miles, original engine, transmission, and rear end.

The real question, always, is: what are your other alternatives?

Diesel? The diesel motors in 3/4 ton trucks are truly amazing. Doesn't really matter what brand, Cummins, Powerstroke, Duramax. They're all powerful fuel sippers (relative). BUT that's why the bring a completely disproportionate amount of money over a gas motor. You'll never make up the difference in fuel savings. But they do tow better. But THOUSANDS better? No way.

8.1L GM? It makes more torque than the 6.0, but it's old architecture and they didn't make many so parts are hard to find and very expensive. The only good thing about a 8.1L is that you could opt for the Allison 5 speed automatic which is a wonderful transmission.

Ford 5.4L V8 or 6.8L V10? This is a Goldilocks thing. The GM 6.0 is so far superior to the Ford 5.4L as to make it a no-contest. More power, more torque, better fuel economy, less complex, more robust. The V10 is a good motor from the power standpoint, but I currently have a 1999 in the mix that I can literally watch the fuel gauge move when driving it like a car. Horrible. And the 5.4/6.8 can have issues with coil packs and spark plug threads. 6.0 GM is better.

5.7L Hemi or 8.0L V10 Dodge? The 5.7L Hemi is an equal to the 6.0 on paper, but likes to be revved so it likes to shift more and doesn't like to pull from low rpms like the GM 6.0L. The V10 is a brute, but also a huge anchor. Again, the GM 6.0L is a good compromise, but close to the 5.7L Hemi. I don't think you can get a Hemi with 3.73 gears like you can with the GM.

My experience with the 6.0 is 15-16 mpg freeway empty at 72-75mph, a little better 55-60. You'll get 11mpg around town.