The Stovebolt Site Forums The Parking Lot Big Bolts most economical hi-speed rearend for 1/12 ton dually?

Any faster than what you are going now, wind resistance is going to be an issue with a 235. A 235 needs RPMs for HP. If you are considering making a 4 door out of the cab, I would consider setting it on a later model chassis that will give you the desired speed.