I have a '13 JKUR with manual trans and am looking to buy my daughter (per her request) a '08 JK Sport with Auto trans. The '08 has 35" tires on 3.21 gears. Was thinking I could upgrade my Rubicon gears (4.10) and give those to her and then upgrade mine to something else. Is this possible?

 

Your Rubicon has a front Dana 44 axle. Her Sport has a Dana 30.

 

Solution: dump the rubi axles into her sport to fix the problems that are coming with her 35s. Then sell the sport axles to offset the cost of the dana 60s and 37s

 

Sure, but the rear should be Dana 44, the same as Rubicon, correct? I'm concerned the 3.21 on the rear, pushing those 35's will cause the jeep to downshift all the time while driving. My 4.10's with 35's cause me to shift to 5th gear in a strong headwind all the time on the highway.

 

The rears are both d44's, but they are built/designed a bit differently. The gears can be swapped, the locker and shafts can not.

If you only regear the rear, be sure to pull her front driveshaft...

 

Well that's just all in right there...lol