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.
Appreciate the insight. I checked it out this morning. Popped the coupler off the inputs haft. U joint on the steering column is free. Looks like a new gear box is needed. This is a rebuilt box that is only about 3 years old. (Not from you guys)
