Warn (now made by Yukon IIRC) sells a kit that retains 5 on 4.5 bolt pattern, costs $1200-1400 and the new non-Warn shafts break frequently with big tires. Alternatively, you can go to 5 on 5.5 bolt pattern with the "Warn" kit.
Mile Marker also sells a kit, runs about $800.
Also, the hubs won't help gas mileage on a TJ. There isn't enough resistance in the axle that can be removed to overcome the stupidly non-aerodynamic barn that is your windshield and grill.