Maintenance of the steering system?

2004 Dodge ram 1500 2WD four door 4.7L engine. Power steering system is malfunctioning. Fluid is full, there may be a leak in the rack and pinion unit under the truck, but working 75+ hrs a week, I haven't had a chance to look. I turn the steering wheel, the pump whines like there's no power steering fluid. I can no longer palm the wheel at a stop, I have to man-handle it. Even driving on the highway, when I make a slight adjustment, it makes the low fluid sound. Any ideas?