Do I need new ball joints when I install this?

Depends on your current setup. If your factory ball joints are worn, this is the time to replace them — you'll have everything apart anyway. If they're tight and play-free, you can reuse them. Inspect before you button everything up.

Will this work with my 3" lift, or do I need something different?

This arm is engineered for the 2-4" range, so a 3" lift sits right in the middle. You'll get proper geometry and angle without binding. Just confirm your lift kit's upper arm specs match this range before ordering.

What hardware do I need to bolt this on?

You'll use your factory bolts and fasteners — the arm bolts at the original mounting points. Grab your service manual for torque specs; they matter on suspension work. If fasteners are worn or damaged, grab new ones before you start.