[TheNewbie]

I have a tired old 2.5 and 32's and can hit 80+ MPH.

I can use 5th gear on the highway as long as I'm not going up a steep hill.

Oh yeah, and i have stock 4.10 gearing as well.

[jonzjeepyj]

How difficult is it to change the gearing to the 4.88's ? Can the gearing be changed in the same differential or do I need to replace the axles to change the gearing ? Is the gearing change for both front and rear axles ?

With the 2.5L and running 33's with 4.88 gear sets will do very well. Your are fine with the carriers that you have if you want a matched set of 4.88's for your stock axles but if you want to go larger then 33's/4.88's then yes you will have to upgrade the axles. The Dana 30 up front will not hold anything larger then a 4.88 gear set, so at the very least you would have to change your front axle. It is not recommended to run 35's on the rear Dana 35 let alone the front Dana 30, although it has been done for a street rig.

Something to consider is that the cost difference of re-gearing with existing weak axles is not much different then doing an axle swap upgrade. If you go with the common swap of the ford 8.8 *(Explorer Axle)* upgrade, you also get rear disc brakes to boot. The only fab work for this upgrade is to grind off and relocate the spring perches a half an inch each side.

[SteveJcoYJ]

Originally Posted by 1998zj

With my 33's and 4.88 gears mine would run 80 mph in 5th gear. I have only had it up to 70 with the 35's I have on there now.

i would never wanna go 80 in a jeep