2003 Chevy Impala Clunk noise when turning at low speed or

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Clunk Felt/Noise Heard From Steering Column, Steering Gear and/or Front Of Vehicle During Turning Maneuver and/or Steering Wheel Rotation (Replace Intermediate Shaft As Directed)

Condition
Some customers may comment on a clunk type noise coming from the front of the vehicle while driving during a turning maneuver. This condition may also be felt through the steering wheel when the vehicle is stationary and the wheel is rotated from steering stop to steering stop. Some vehicles may only exhibit the noise once for every 360 ° of wheel rotation. On all other vehicles, this clunk noise will be noticed during low speed acceleration or deceleration, typically in light turns of the steering wheel or when applying/releasing the brakes.
Cause
This condition may be caused by a "slip stick" condition resulting in the clunk noise or feel through the steering wheel.
Diagnostic Tip
IMPORTANT:This condition is commonly misdiagnosed as originating in the steering gear and has resulted in the replacement of numerous steering gears without correcting the concern.

Attempt to duplicate the customer's concern and isolate the I-shaft by following the procedure below:
Locate a large area (parking lot) where the vehicle can be turned in a tight circle.
Turn the steering wheel to the right and/or left all the way to the steering lock, then off the steering lock a 1/4 turn.
Drive the vehicle approximately 5 km/h (3 mph) in a circle, preferably over rough pavement or seams on the road surface.
If a clunk is felt in the steering wheel, the MOST likely cause is the I-shaft - not the steering gear. Continue with the correction.
Drive the vehicle straight ahead at idle speed while applying and releasing the brake pedal. Listen/feel the steering wheel for the clunk-/noise condition.