Are you talking about the rear lower control arm ball joints? You can get aftermarket ones for around $30ea. I ended up grinding down a ring spanner so it was thin enough to get around the nut (after I removed the split pin), like most jobs on a GTR it is not awesome fun.
To get the ball joint out you need a press; I used the one at work and made my own drift. R33 GTS and GTR should be the same I assume it is the same for R32's and R34's as well but I do not have experience with either of them.