Steering help

I just bought a 2001 Jeep GC limited. Before i bought it i told the dealer there were some things i wanted fixed before i would buy it. Well one of those things was the steering box since it turned hard to the left. Now that they fixed that it turns great. But my problem now is every once and a while when i turn it all the way to the left or right(mainly right) it makes a grinding noise. I checked the power steering fluid to see if that was alright and it was. I don't know if it is something to do with the steering box they put in or what. Like i said it only seems to make the noise when it is pretty much turned as far as it can go in either direction. I have been tryin to find stuff online and the only thing i can find is maybe the viscous coupling is going bad but i have no idea.
Any suggestions would help???

There are stoppers when your turning your wheel to a full left or right. If your running over size tires/off set rims sometimes ur wheels will hit the frame. These stoppers can be adjusted. Use a "release All" or kind of product to loosen them up.