well according to everyone on this forum if you r going to upgrade just go to a D60 forget the 44
can of worms open again:
What do you break on the D30 that you won't break on the D44? (i.e. why are you considering an upgrade) My experience is with an XJ (super special, reverse cut, non-disconnect) D30 front/D44 rear with 35" MT/Rs.
D30 issues: (from my experience)
1) axle joints (297 or 760)
2) bent housing (housings in my case)
3) ball joints
4) unit bearings
D44 advantages:
1) potentially stronger housing (depending on which D44 version, but some have decent axle tubes and definitely a stronger 'pig')
2)slight edge in ball joints
3)commonly available with spindle-inner-outer bearings
4)better brakes available
5)slightly stronger ring/pinion than a reverse D30, but I didn't have any issues with the strength of a 4.88 ring/pinion (and that pinion is 'cute') in my D30
D44 disadvantages: (again, my opinion)
1)AXLE JOINTS (they're the same as the ones I broke a LOT of in my D30 that took out the shafts)
IN MY OPINION, I needed an upgrade to my axle joints. I could go exotic (CTM or similar) and get some alloy axles (Warn or Superior were my choices) and spend about $800-1200 (this was a few years ago, so pricing may be off a little), OR I could get bigger stock axle joints and still have an upgrade path if they became an issue (D60s have CTM and alloy axles available) and not have to go through building a whole other axle again. The choice was simple for me when you can get a D60 for about the same price as the upgraded axles in the D44 (or even the D30). After seeing a few Warn shafts and CTMs shred themselves in a D44, it made it that much easier to do the 60.
It's your money, spend it how you want. I'd rather spend mine on fuel for trips rather than parts. If I ever have an XJ again, I'm sticking to the reverse D30, building a decent rear axle (XJ D44, 29 spline 8.25 or even an 8.8) and sticking to 33" tires and about 4-5" lift. They're actually a decent little rig if you stay to that area. You'll start stressing the unibody and rebuilding all kinds of things as you move up in tire size from 33". Not worth it to me. This is my opinion and is worth exactly what you paid me for it.