Brer Rabbit
Pursuit Specialist
- Joined
- Feb 5, 2005
OK I have an 05 3500 4x4 (not a dually) with that gas guzzling 8100 and Allison trans and 4.56 gears. Love the towing power but not the fuel economy as that dash computer shows an average of 8.6 mpg running around the city. On the expressway, driving really easy I have to fight to get10-12 mpg. I was wondering if a drastic change in the gear ratios would help this truck to get 16-17 mpg on the expressway. A friend told me he yanked the 4.10s and put 3.73 gears in his 2006 6.0 truck and he saw an incredible difference of like 5 mpg. He went so far as to suggest I go with 3.42s and believes it will not hurt performance. Has anyone tried this type of mod to a stock truck with a similar drivetrain? I know I will have to have the dealer recalibrate the speedometer but I would like to hear some thoughts on this please.