Not sure on the ball joints, but you should be able to take the old one to the parts store and get them to match it. You know it's a chevy truck, so you should only have 4 or 5 to choose from at the most. I used a tool that snap on sells. Cost 45 and has a lifetime warranty here is the link:
http://buy1.snapon.com/catalog/item.asp?P65=&tool=&item_ID=8154&group_ID=946&store=snapon-store&dir=catalog
Hope that helps.