Welcome to 1/2 ton stuff, like Matt said, if you run 1/2 ton gear, and wheel hard, you will become very familiar with changing ball joints on your D44. It's just one of thoese things. I have used Spicer from the start, and they are about the best they offer. Bought mine from Autozone and have the lifetime deal. I have two sets of them, the set in the truck and an old set of uppers and lowers, when the Death Wobble come a knocking, I zip down to Autozone and give them my receipt and old set and head home to change. It now takes me about 2 hours to change both sides.
Best bet is to get a ball joint tool cheap and have it handy. I use antisieze on the joints once I remove the retaining clip on the top joints I can drive them out with a hammer, don't even need the tool anymore.
It's just what happens when you wheel 1/2 ton stuff. It's really hard on the ball joints.
As a side note: ALWAYS CARRY A SPARE UPPER AND LOWER BALL JOINT ON THE TRAIL. It will destroy a lot of things if you break a joint and try to bootie fab and wheel your way out of the trail it will tear @hit up.
Good luck.
Rob