You need a big monkey wrench and you need a vise, other than that....it's a piece of cake.
Get the drain plugs out.
Get the handle off.
Get the stem retaining busing out.
Technically the stem could be pulled straight out now, but after 33 years it's real comfy and does not want to do anything other than move in the one direction it's been been doing for all those years, open, closed.
Place hose barb elbow in the vise.
Do the big wrench thing.
Now place the large ball retaining bushing in the vise good and tight and do that big wrench again with gusto. You may need a lot of gusto here unless you have a proper vise as I did not.
Get good pair of vise grips on the flat of the stem and wiggle it straight out. If it's a tough one, you can use a screwdriver to pry the vise grips as you pull.
There you have it.
A repair kit comes with a new ball, two ball seats, and two o-rings. After you pry out the old seats, clean it up really good install the seats and reassemble in the reverse order.
I got this many apart in one day.