Most of the ball joint sockets are 3/4" drive... If you don't have a 3/4" drive, then get an adapter for a 1/2" drive to 3/4" drive...
then go to the hardware store and get 3 foot of metal pipe with a diameter big enough to fit on the end of your 1/2" wrench to help give more torque to break them loose (cheater bar)...
Soak them in penetrating oil, then put the cheater pipe on the end of the wrench handle to give you more torque/leverage to break the old ball joints loose...