Zen, I have a hammer . Why do I need a grinder?
'Cause you don't have a press. The best way to get ball joints (and the bushing on the other end of the arm) out is to have someone with the proper tools and skills to press them out and press the new ones back in. If you use the urethane bushings, you don't have to have them pressed in like the stock bushings, but you still have to get the original bushing out.
If you MUST do it yourself, take the arm off, grind the bottom off the joint and knock the guts (the ball/stud) out of it. Then you can use a die grinder and carefully grind a slot in the side of the outer part of the joint. If you don't have a die grinder, I have assembled a hack saw with the blade upside down and running through the joint and cut through it that way. Where there's a will, there's a way. OK, maybe not a good way, but there's a way. You want to cut through the wall of the joint, but not touch the arm it's pressed into. If you can do that, it releves the stress on the joint and it's pretty easy to tap it out with a hammer. If you can find something the right size to lay it on and the right size to fit against the back of the joint, and you are VERY careful and VERY lucky, you can drive the new joint back into the arm without damaging it or bending the arm.
Here's a better way: Listen to Ret.Bugtech! There's a reason most people pay a good mechanic to replace ball joints. Do it yourself and you'll know why. :wink:
Which ever way you do it, you MUST (I don't mean should, I mean MUST) take it to a GOOD alignment shop and get the front end lined up when your done. If you are not going to have it aligned, don't bother working on it at all. You won't be able to hold it in the road if you don't.