Right now my '03 4.0 is stock. I want to get 33's, 12.5 wide tires and lift it 4 inches. After reading several threads in the forum, I seen that many people upgrade their axles to handle the bigger tires. I don't have a rubicon, so I am pretty sure I have a 30 / 35 setup. Upgrading the entire axles looks pretty pricy. However, I saw there is a superior axle kit. The product description says that it upgrades the splines from 27 to 30 (the same as a dana 44)? What does this mean? Is it still the same diameter as a stock 35, only they managed to cut more splines in it. Or is it actually a wider diameter? How is it superior? I would like the ability to add lockers in the future.