Ok, this has been written up in the FAQ but it still comes up. The TJ Dana 44 rear is a Dana 44 housing with Dana 35 axle tubes and ends. The axle, R&P, carrier are D44 but the brakes, axle tubes, retainer flange and pattern are all D35.
The front D44 on the other hand has a standard housing and I think axle tubes. The inner axles are 30 spline as well as the carrier and the R&P are D44. What's not D44 is the outer knuckles. Those are all D30. It so happens that the later D30's use the D44 size U-joints so the outers can be used with the inners. The other part that's D44 is the inner knuckle though. You cannot swap the outer knuckles for D44's or even CJ D30's.