Nothing and yet quite a bit...:rofl: Really though there are many differances but the front rubi 44 is not much if ANY better than a D30.
here are thier specs...
Dana 30 (181 mm) - 1997-2006
* Front axle used on all TJs except the Rubicon model
* Stock gear ratio options = 3.07, 3.55, 3.73, 4.10, 4.56
* Carrier break = 3.55 / 3.73
* Open carrier - no Trac-Lok limited slip option
* Ring gear diameter = 7.2"
* Ring gear bolts = (10) 3/8 x 20 RH
* Low pinion (short pinion)
* Pinion shaft diameter = 1.376"
* Pinion shaft spline count = 26
* Axle shaft diameter = 1.18"
* Axle shaft spline count = 27 both inner and outer
* Axle shaft u-joints = 5-760x / 5-297x
* WMS-WMS = approximately 60.5"
* 5 on 4.5" bolt pattern
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Dana 44 (216 mm) Rubicon- 2003-2006
* Standard front axle used on all Rubicon model TJs
* 4.10 gears
* Tru-Lok selectable pneumatic locker - open differential when unlocked
* Ring gear diameter = 8.5"
* Ring gear bolts = (10) 7/16" x ??
* Low pinion
* Pinion shaft diameter = 1.376"
* Pinion shaft spline count = 26
* Axle shaft diameter = 1.31"
* Axle shaft spline count = 30 inner / 27 outer
* Axle shaft u-joints = 5-760x / 5-297x
* WMS-WMS = approximately 60.5"
* 5 on 4.5" bolt pattern
Note: The outer axle shafts, unit bearings (hubs), knuckles, and brakes are the same as those found on the TJ D30.