Engine/Transmission (1998.5 - 2002) Fuel Economy

[cscott]

I am planning to put 19. 5 wheels on my dually. When i do I plan to swap the rear gears.



The question I have is should I change the gears so they are the equivilant to the stock 3:55s or should i shoot for the 4:11s.



I have heard and it makes since to me that the 4:11s are less stressful on the auto trans.



But my main question is when running unloaded what sort of fuel economy diference is there between the 4:11s and the 3:55s?



I pull a 16K goose neck car hauller. So I know the 4:11s will be better for that.

 

[kscheffler]

I have a 6 speed with 4. 11 and only 7k miles but I am getting 16. 8 mpg unloaded. My buddy has the same truck with 6 speed and 3. 54 and he is getting 20 mpg so you are looking at a 3 mpg difference.