El Robot, is your truck 4WD or 2WD? Auto or stick? If it's a 4WD auto, it's got a the 4.90 gears with the H233b rear end. If it's a 4WD stick, then it's got the 4.63 gears in the same H233b.
The axle shafts on the H233b are actually larger than the Ford 9" rear end. Which means that they're considerably larger than the Dana 44. The ring gear size for the H233b happens to be 233mm (crazy, right?!) which is 9.17", whereas the Ford 9" has only a 9" ring gear. So the strength of the H233b is there, no doubt. It's a lot stronger than the Dana 44 to be sure.
I've done a lot of superpacks. Both for myself and for people. I know of several people that still running the diffs I superpacked almost 10 years ago. No issues.
All you do is to pull the 3rd member out of your axle, measure the backlash of the ring and pinion, remove the carrier from the 3rd, split the carrier, add one steel (not a friction) plate to both sides, reassemble the carrier (make sure the threads are clean and dry in the carrier, the bolts are clean and dry and then use loctite on the threads), reinstall the carrier into the 3rd (setting the backlash back to where you found it, don't be tempted to tighten the backlash up, it will induce a 2nd pattern, cause noise and could even start scaling the teeth of the ring gear), reinstall the 3rd into the housing (don't have to use a gasket between the 3rd and the housing like Nissan did originally, just use some good RTV sealant, I like either black Right Stuff or the grey Permatex) and fill the axle with plain 80W-90.
You'll get some chirping of the tires around corners because now you're running a superpack/spool in the rear end. I've had the back end of my first X on one rear wheel, running 35's, SuperCharger pounding away, 4000 rpm and 4.90's with the single tire smoking and it never broke loose. Unless you spend the time (and money) to take your LSD apart, measure the pack height, set it a little tighter (closer to the older Pathy packs) by buying different height friction plates, putting it back together and measuring the breakaway, and then doing it all again until you get what you want, then I'd suggest either the superpack option (it's just spooling your rear end) or the ARB.
If you can save for the ARB, you will save the money on tires. If you have access to tires cheaply enough, or it's not your DD, then the superpack is an option.
But don't swap in a Dana 44. Although locker options are far and wide for them, unless you spend the money for full chromo axles, beefy cover, etc., then it's just a step down for what you want. Even if you're planning on doing the SAS in the future, the minimum I'd go is the Ford 8.8" with the disc brakes. Even then, you still have plenty of options for the locker, get the crush sleeve eliminator kit, you can use the center speed sensor (with a Dakota Digital adapter) for your ABS, I think that Moser sells chromo shafts and you can order them with the 6 x 5.5" pattern, swap in a brake Master Cylinder from a Pathfinder that had 4 wheel discs (have to swap out the residual valve that's on the outside of the passenger's side of the frame by the fuel lines with the same residual valve for the Pathfinder too) and go to town. But the ratios for the ring and pinions won't be an exact match to the front diff, so you're still stuck in that manner (as long as you're within 5%, you're OK for slipper conditions), you'll have to modify your driveshaft to fit whatever rear end you pick and then there's the welding, brake lines, ABS, shocks, etc.
If you've got the stick 4WD, grab the front and rear 3rd out of an automatic 4WD and swap them in. If you're running larger than stock tires you will love it! I just put in a set of ARB's for a friend that was putting the 4.90's in his manual Xterra. Way cool!
