Get the new chevy. I am on my 2nd one in 6 years and had a powerstroke inbetween. I can pull anything with my 6.0 I could with my diesel. The powerstroke got better mailage with nothing behind it than the gas chevy but for the 5000 dollar diff. I can buy alot of gas. I have pulled over 12000 lbs with the chevy and had no problems. the older ones with the 454 will only get about 10 mpg empty and 6-7 loaded.