Power steering pump, or gear/box?

I'm leaning toward the pump is bad. 2005 Dodge Ram 2500. Turns fine to the right, but turning left is like trying to turn a 1948 Mack truck sitting still with your foot on the brake.
Yeah, it's that hard to trun at a stop, and feels like normal standard steering when rolling a little. And it is not just when trying to go left from center. It doesn't matter where the wheel is.