I am pretty sure my ball joints are bad. I put a 2" leveling kit o the front about 1 year ago. How can I tell if I need to replace the upper or lower control arm w/ ball joint?

 

If you are going to get in and replace the ball joint, you really ought to do them both at the same time, and both sides. Why waste the labor when the parts are so relatively cheap? Even if your labor is free, alignments aren't...

Do yourself a huge favor, and just order the UCAs, and lower ball joints for both sides, and find a warm space to work... You might even consider swapping out the tie rod ends at the same time, just get it all done and tight again...