I have a '97 F350 dually extended cab with Powerstroke diesel and automatic. Suspect that I have a 4:10 rearend. Just bought a fifth wheel RV with a gross vehicle weight of 13,300 and tongue weight of 2,000 empty. Run empty 90% of the time and mileage is horrible. Thinking of changing rearend to 3:73 to improve my fuel economy when running empty. Tow rating guide says that I will still be within GVWR for the truck. What will this change due to towing performance? Would appreciate any other comments pro or con to this idea. Thanks.

 

 

I would suspect that you are losing most of your mpg to wind resistance and not the weight, you may want to invest in a 150$ air dam befor 500$ in to the rear. the 410s' are most likley 411s' and should put you right in the bottom of yoour peak power curve at highway speeds. Hope this helps and good luck.

 

I have an air dam already. What I am wanting to do is improve my mileage when I am not pulling the trailer. Appreciate the input. Thanks. Gary