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.
Generally if the pump was the problem you would feel it in both directions as the pump does not know which way you are turning. This could be either a steering box or if a 4WD truck take a look at the universal joint on that side, if they are binding up it can create issues like this.