How do you change the lower ball joint on a 1996 volvo 850?

i bought a new ball joint to replace but the new one has 3 studs where as the old one does not, im just a little comfused. please help
How do you change the lower ball joint on a 1996 volvo 850?
as a suggestion, from volvo the lower control arm is inexpensive,. this comes with new ball-joint and both control arm bushings installed, plus new bolts and hardware, on a clean car [no rust] this assembly can be replaced on one side in about 20 minutes.

by your description the ball joint that was sold to you is for a pre-94 model that had a cast aluminum control arm.not the triangular.one made of steel that you have
How do you change the lower ball joint on a 1996 volvo 850?
you need a hydrolic press to change ball joints properly. clowns try to do it with a hammer but it never works. Take it to a shop with the right equipment