Power steering whines and scraping noise.

[Outlaw_71]

Well now i take my truck offroad alot and i knew eventually i would have problems with my steering. The trouble is how to pinpoint the part that is causing the problem and decide between rebuilding, replacing or just patching it up. I have had the seal replaced on the steering box before but my mechanic says it'll just bust again if the box is bad. The problem is that it hums, feels tight and sometimes wanders a bit. It did leak for a while but it hasn't since i have been adding prestone ps fluid with stop leak to top off the resorvoir. It is still using fluid pretty often. I also hear a scraping noise in mid turn sometimes and the engine feels like it is about to lose power when this happens. The chassis is a 77-87 4x4 model with a spring lift and 33" tires. What things should i check to decide what is wrong? Let me know if people need more info or pictures to help me out. Thanks for any advice in advance.
-Kevin

[Mudder]

I have replaced both the pump and the gear box on my 77. Think about the age of it and what they do. Check out your steering links and make sure you don't have anything binding also. And while you are doing that makes sure there are no cracks in the frame around the gearbox and that frame is not flexing at the front cross member.