I happen to have come across a pair of low mile stock 3.55 axles. my stick has 3.07 gears, what can I expect my fuel mileage change to be if I put them on and what about RPM changes. with the 3.07s I am at 2100-2150 at 75 MPH.

 

I'm curious too; with 235/75R15s and 3.07s 5th is about useless in my TJ. it was worse useless, when I had the 31s on it.

 

anywhere from 1-3 mpg increase I would say. talk about 3.07's sucking *** with 31's, try 33's

 

http://www.grimmjeeper.com/gears.html

DO it, you will not regret it at all.

 

Cool gonna get it done,thanks.

 

why didn't they put 3.55s in 5spd in the first place?

 

thats exactly what I am thinking, because almost every other manufacturer puts lower ratios into vehicles with manual transmissions

 

I think it's because 3.55s would turn first into a granny low type of gearing. From what I understand the 5 speeds case or internals cant take the torque. H*** most people that bought cherokee's in the first place back then were "yuppies" and had no idea what what a grannny gear was, and would have probably grenaded their tranny. Or I could be wrong and it was an emissions thing. (sorry if I offend anyone with the "yuppie" comment)