I know a friend who has a f150, and he went from 245 to 285's, and his mileage decreased by 2mpg, so I'd assume that from 265 to 285 would only be about 1 mpg.

 

Since these Michelins (at least two of them are original - other two used from local tire shop) have only lasted 120K I think it's only right to get the same tires again!

Read too many iffy things about some other brands anyhow....

 

Your overdrive ratio is killing you. Put on a GV and you will get 22+ at 65mph. My dually does all the time. At 70 I am averaging 19.8mpg. I think the 24valves sound better on the outside and the CR sound better on the inside. 4 doors is better than 2 suicide doors. Track bar stinks on 24 valve. Power stock to stock isnt even close. All in all I miss the 24 valve. I do like the bodystyle of the 2nd gens better and the dash is better on the 24valves. I prefer the G56 to the 5600. I hated where reverse was. Plus shifting was very notchy. Find me a 98 12v dually quad cab 5 speed and I would sell to get that.