I have 120K with the stock ball joints and within the last year starting adding 33s, 35s, and 37s. Getting ready to change them soon... but I would think they would last longer than that?
Someone can back me up, but to check and see if you need ball joints you want to
1. lift the tire off the ground
2.put one hand at the 12'oclock and the other hand at the 6'oclock
3.try shaking the tire with both hands in this position
4. if the tire moves easily, then its time for new ones.
I think that's the method for checking on new BJs, but not 100 percent