GM-GMC: sierra c3 shutter, truck shutters, power steering pump

Question
I have a 2001 sierra c3 and when I drive it for about 15 min. and try turning into a parking spot the truck shutters it feels like the front end. thanks

Answer
There are a number of things that can cause a shutter type feeling.  A dry ball joint, or any dry steering component can cause a shutter feeling.  A failing power steering pump can also cause a shutter feeling.  The symptoms you are describing are usually associated with 4WD trucks.
If you can reproduce the shuttering noise in an empty parking lot, try having someone move the truck forwards and backwards while you listen or look from outside.  Putting your hand on a fender can help narrow your search to one side or the other.  Also try putting the front end up on jack stands and turing the wheels from side to side to see if you can located the cause of the shuttering.  Be safe, don't get too close or infront of the truck while its moving, no matter who is driving, trust me I speak from experience.

Hope this helps.