well after finally catching up for the hurricane and recovering from my other job of working so many days straight with hardly any sleep, i can tell you the verdict. 8 mpg with my sierra and that's a mixture of city and highway. im looking at a 6.0 now. 2006 f250 king ranch. only thing that worries me is that its was sold in jan of 06 so its one of the earlier 6.0s which had more known proabs then the late 06 6.0s. according to car fax, its never had the heads done, just other minor stuff. its has 50k on the dash. and then reading the 6.0 vs 6.4 on the various forum sites out there. its the same mixed reviews. some say theve never had proabs some say its been nothing but a headache and some say yeah its been a decent truck lol. so i guess its just luck of the draw and what you want. 6.4 gets worse gas mileage, sounds like a danm truck until you roll the window down and accelerate. 250s with the 6.0 looks bad ass and so do the trucks with the 6.4 in them. the new 2012 trucks with the new 6.7 for one sound like complete s^^^ and look like complete s^^^. my dads got the 08 f250 with the 6.4 and only have the radiator hose break (known issue) and something in the steering colum with wiring go bad. hes got 56k on the dash. so i mean, its luck of the draw but isnt it with any vehicle lol. one person will tell you they wouldnt touch it with your dick and some will till you thell touch it with theirs lol.