The 460 will be a much better puller, but you pay for it in fuel mileage. My old 460 powered one ton crew cab never got much better than about 12 mpg!! Now we have a diesel, gets at least 17 mpg and never seems to be working when pulling a trailer. If those were my choices, I would go with the 460, just be aware of the low fuel mileage. Doubt the 400 would do much better, never have ran one, but have friends that did. Mileage with the 400 wasn't any better than my 460 according to them.