I did the same thing to my '04 Dodge Cummins at 100,000 miles. I now have over 250,000.
If I had it to do over again I don't think I'd do it. Hubs have always been important on four wheelers, but this setup hasn't really proved to be a big advantage.
First, I saw no increase in mileage. If there was any it was so small as to be insignificant, and I couldn't measure it. A 2-3 MPG gain is not in the cards. There just isn't that much friction in the front axle compared to the rest of the truck. If you are dong it to save money, and that must be why you are hoping for the increase, the cost of the system is so high it would take a very long time to pay off. Plus the new setup requires more maintenance to survive.
Second, I got the Dynatrac hubs and one failed right away. They had a plastic bearing in them originally and have since improved them. They make a few advertising claims about them that are misleading, something about how they default to lock. But when you see the setup you'll see it's just a spring. Really no advantage that I can see. The Warns actually work better and are plenty strong, but they might stick out a bit farther.
Third, the Dynatrac hubs have a very poor indicator for lock-unlock position, it's just laser etched with lock and open. Before long you can't read it. Before long they begin to corrode and look bad. The Warns are far better for reading the position and corrosion resistance
Fourth, The stub shaft support bearing went out on mine and I had to buy a new outer stub shaft, U joint, bearing and seal all within about 50,000 miles. This setup is far higher maintenance and if you want it to last you have to pull it all apart an grease it regularly. From what I understand this problem is not uncommon because water can get in and there is constant pounding from the axle shaft even when not in 4wd. To grease it you have to pull the axles out of the truck which requires removal of everything but the knuckles. By the time you get the bearing out to thoroughly clean it you might as well replace it because it's hard to press out and requires a special tool. This is a time consuming and expensive piece of maintenance.
Fifth, it's an expensive kit. So if you are doing it to save money, you're dreaming.
On the plus side it saves wear on the front driveshaft Ujoints and stub shaft joints and it allows 2WD low. It also gets rid of the unit bearings and that is a plus. But that's about it. My unit bearings were still fine at 100,000 miles, but I wanted hubs. Now I'm not so sure. And when the original Ujoints go out they can be replaced with greaseable ones that might last the life of the truck.
Be sure you replace your ball joints! I know you mentioned that, don't change your mind. They are a known weakness and this is the time to do it. Whatever you do, don't use Moog. They are not made well and cause a lot of steering problems. Dynatrac makes very nice ones. Here's the deal wit the Dynatrac joints: They call them rebuildable and greaseable. But they are not easy to rebuild and the "greaseable" claim is misleading. You can grease the top one, but not the bottom one, at least not with any grease gun I've ever seen, unless you pull the axle out of the truck. Originally they were not greaseable, but they changed them because everyone wanted greaseable, and all they did was tap in a zerk where you can't get to it. I do think they are nicely made, though and I'd use them again. They actually have a ground ball in them instead of the rough forging that Moog uses and the truck drives well with them.
