GM posted a TSB yesterday (1/31/07) for the infamous steering shaft clunk. I checked with my dealer and they already have them.
Subject: Clunking Noise Under Hood and Can Be Felt in Steering Wheel and/or Steering Column (Replace Upper Intermediate Steering Shaft (I-Shaft) Assembly) #00-02-35-003M - (01/31/2007)
Models: 2002-2006 Cadillac Escalade Models
1999-2007 Chevrolet Silverado Models (Classic)
2000-2006 Chevrolet Suburban, Tahoe Models
2002-2006 Chevrolet Avalanche
1999-2007 GMC Sierra Models (Classic)
2000-2006 GMC Yukon, Yukon XL Models
2003-2006 HUMMER H2
Attention: This Service Bulletin DOES NOT include Mid-Size Utilities such as Buick Rainier, Chevrolet TrailBlazer Models, GMC Envoy Models or Oldsmobile Bravada. Refer to Service Bulletin 02-02-35-006A or newer for Mid-Size Utilities.
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This bulletin is being revised to update the repair procedure with a permanent fix. Please discard Corporate Bulletin Number 00-02-35-003L (Section 02 -- Steering).
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Condition
Some customers may comment on a clunk-type noise coming from under the hood that also can be felt in the steering wheel. These conditions may be more noticeable when turning at low speeds on rough road surfaces.
Diagnostic Tips
Use the information below to help diagnose the source of the noise.
• Frame Snap and/or Popping Type Noise -- A frame snap or popping type noise can be duplicated on rough or smooth road surfaces with steering wheel input to the left or the right. This type of noise can be HEARD and is typically louder with the windows rolled down. For additional information, refer to Corporate Bulletin Number 03-08-61-002F or newer -- Snap/Popping Type Noise Coming from Front of Vehicle (Remove Front Crossmember, Change Fastener Orientation).
• Intermediate Shaft Clunk -- Intermediate shaft clunk is heard and FELT in the steering wheel and/or steering column area, typically while driving on rough road surfaces with steering wheel input.
Correction
DO THIS
DON'T DO THIS
Replace the I-Shaft with P/N 19153614.
Do NOT lubricate or exercise the I-Shaft.
Important:
• I-shaft P/N 19155614 has been designed to replace previous designed dampened and non-dampened I-shafts. The physical difference in the yoke size will accommodate all vehicles listed in this bulletin.
• Due to the design of the new I-shaft, it is not possible to lubricate/grease the I-shaft.