Yes, they are a press fit. It can be done on the car. After clearing the strut from the ball joint, support the bottom of the control arm with an axle stand, and smash the ball joint out with your BFH, then place the ball joint in position from the bottom and support the ball joint with the axle stand, having a short piece of exhaust tube or similar to sit the ball joint on helps. Then tap the control arm down, forcing the ball joint up into position. Hit the control arm in alternating strikes on opposite sides of the ball joint to make it go in evenly.
Or you could just use a press and press the old one out and the new one in. This requires total removal of the control arm of course.
they are kind of a press fit. There is special tools for it, but there is also backyard methods or you could just take the control arm off and drop it over to a suspension place and get them to fit the ball joints for you. But you can do it yourself.
Bash the old ones out with a hammer. Just put an axle stand under the control arm and go for gold - be careful not to damage the control arm.
Fitting the new ones, I find it easiest to put the new ball joint in the freezer for a few hours so the ball joint contracts in size. Fit it up from underneath the control arm, put a socket large enough to fit on the outer housing of the ball joint and then slide a jack underneath. Jack some weight onto the balljoint, place a lump of timber against the side of the control arm (as close as you can to the ball joint) and then belt it with the hammer several times. The ball joint should start sliding into place.
If you have trouble getting them out mine in my VK were 20+ years old when I chenged them, I bashed the living $h1t out of them and they wouldnt come out, used a ball joint remover fork and it still wouldnt budge. left it loose drove in and about to drive back intot he driveway and out it fell, to the nut anyway.
You can use an oxy to help loosen them also.
far out guys! i have no idea how you do it with a hammer, i have smashed that thing, froze it for two days, heated up the arm with the oxy, took the control arm off and stuck it in the vice etc etc etc