You can never just do one thing. Everything you do leads to something else. By the time you get that upper ball joint replaced, you will probably have replaced the entire front end suspension.

 

It is very straight forward and not to be contrary to what some have said but you do not have to remove the upper control arm to replace the ball joint. Jack it up under the frame as you mentioned, loosen (don't remove) the ball joint castle nut. You can either use a fork or a few sharp raps with a hammer to separate the joint from the spindle. Remove the bolts holding the joint to the control arm and the castle nut and it's off. You may have to pry the lower control arm down to remove the spindle from the ball joint. It's not a big deal.

 

Guys you can do the uppers and lowers with the spring in very easely. Jack up the car and put it on a stand, then lift the wheel until you can put a 2/4 between the upper control arm and the frame rail. Loosen the castle nut, do not take it off, and smack the spindle until it drops out. Than use a air chisel and chisel off the four rivots. If the spindle doesn't drop down far enough then you have to remove the strut arm and maybe the sway bar link. I just changed all 4 of my ball joints a few weeks ago. Any other Q's I'm at pfmengel@yahoo.com
Also in your service manual you will see that the uppers can have .20 of play in them and be all right. The lowers can't have any play. Have fun Rick