What kind of fuel economy would i get with the 3.55 vs the 3.08 gear ratio in my 4.9L inline 6 (300.6)

 

MPG has LOTS of variables.
For instance my 93 5.0 2wd lwb w/3.55s gets 18mpgs. I do about 95% driving on interstate 65-70mph. Im very easy on the truck and never use the cruise unless the road is very flat. We are very close to sea level here so that helps also.

All in all the first few months you will probably see a 2-3mpg loss due to the fact take offs will be a bit more "powerful". Once you learn to drive it for optimal mpg Id guess about 1mpg loss overall!

 

Better mileage in town, less on the highway.

 

With my truck having the k& n cold air intake system and the poweraid throttle body spacer do you think the 3.55 gear will help my engine get out of a bog pulling trailers . And do you think it will help my fuel economy??

 

What all would i need to change the gears from 3.08 to 3.55

 

You didn't say but truck must be a 5spd. I think you'd be disappointed after spending the money because you won't gain much towing power. That I6 will pull most any trailer but just not very fast. You'll be able to take off a bit quicker with 3.55 but that's about it. I have an I6 but they have their limits.

 

Mine is actually an automatic with 3.08 gears

 

It would be worth it then.

 

Ok tks for info

 

Easiest to find a truck with a 3:55 axle and swap the whole thing if you're not familiar with setting lash on gearsets.