Steering problems

If it is only hard to turn one way, you most likely have a rack and pinion steering gear and there is excessive wear in the spool valve. That lets power steering fluid bypass the power piston. The fix is to replace the assembly and have the truck aligned. This has been a real common problem on GM vehicles since the late 1980's. Look for a rebuilt assembly from an aftermarket re-builder like Moog or Federal Mogul. Those will have the spool valve's soft aluminum housing bored out and a stainless steel liner pressed in. The Teflon seals grind into the housing and cause this problem.