how to diagnose steering issues
 

my 2004 is getting hard to steer!!! has 227,000 miles on her. original pump and rack. pump does not make any buzzing noise. I put front up on stands, pulled return line and extended it into gallon jug. I started truck, turned wheel back and forth while watching reservoir. I kept filling reservoir, repeating until I was confident I had fresh fluid thru system.
Truck just steers hard. I think all the suspension/ tier rod ends are good. trying to determine if pump or rack needs replaced

Have you checked the lower ball joints for free play?

WITHOUT starting the truck while it's on jack stands, how does the steering feel?

What did you use for fluid? The only stuff you should use is Mercon V-compatible ATF.