I have to change my lower ball joints and i wanted to know if i need an alignment after i do it?

There is a good chance that the new ball joint will not place the knuckle in the exact same position as the worn joint. It's always a good idea to check alignment whenever replacing front suspension and steering components.

Also, before replacing your old ones, try and grease them along with the other 10-11 grease fittings on your front end.