WHEN I AM STOPPED AT A LIGHT, STOP SIGN, OR ANYTHING ELSE TO THAT MATTER AND I TURN THE STEERING WHEEL AT LEAST A HALF TURN TO EITHER SIDE, THERE IS A RUMBLING / CLUNKING / CLICKING / SPUTTERING TYPE OF SOUND ... IT DOESN'T SEEM TO HAPPEN AT HIGH SPEEDS, ONLY WHEN I AM STOPPED OR MOVING VERY SLOWLY ... WHAT COULD THIS BE ...??????? THANKS

 

First thing is turn off the caps lock.
Second is a better desciption of the noise and where it's coming from.

Clicking may be the signal cancelling mechanism.
The other noises you describe, I'm not sure but any not obvious steering issues on Mustangs I tend to point towards frozen ball joints.