Here are just a few of the TSBs / STBs that are out for the 1999 - 2005 Silverado 4x/2x, dealing with CLUNKING, BRAKE FAILURE - These items will be fixed by GM even out of warranty.
BTW; If you still have any warranty left, you can buy an extended warranty for your Silverado as long as you still have warranty time left.

CLUNK;
Recall Data: 01/07/2005
Components: POWER TRAINRIVELINERIVESHAFT
Units Affected: 98221

BRAKE FAILURE- antilock ASB
Recall Data: 02/28/2000
Components: SERVICE BRAKES, HYDRAULIC:ANTILOCK
Units Affected: 10674

BRAKE FAILURE - RUBBING OF LINES
Recall Data: 10/30/2000
Components: SERVICE BRAKES, HYDRAULIC:FOUNDATION COMPONENTS:HOSES, LINES/PIPING, AND FITTINGS
Units Affected: 1383922

ANTI LOCK FAILURE
Recall Data: 08/29/2005
Components: SERVICE BRAKES, HYDRAULIC:ANTILOCK
Units Affected: 1353718

PARKING BRAKE FAILURE - PEDAL LOW WHEN DEPRESSED
Recall Data: 04/22/2005
Components: PARKING BRAKE
Units Affected: 90242

See this site
http://www.internetautoguide.com/aut...500/index.html

I had all of these item fixed by GM out of warranty except one, the CLUNK people are talking about WAS fixed at 91k. It is not chains, u-joints but the driveshaft which will have a harh, negative efect of the entire drivetrain. GM knows this and will not fight you over this!@!
You deserve these items to be fixed and GM will back you, just be nice but insistant.
GL
Greek