Glad I found this forum. In February 09 I purchased an 03 silverado regulary cab v-8 w/ auto from and estate. It has 17,500 miles and paid $7,500.00. Shortly after the purchase I began hearing the clunking noise when steering left. I read all the forums about the steering shaft. I then called the local dealer and they said it would cost around $200.00 to fix and when asked if GM would take care of it, they responded with a "No, not likely"
I then called the customer service number in the owners manual. Yes I spoke with a female foreigner who was hard to understand. After getting my information:name, VIN number etc. She said I needed a "proper diagnosis". She then called the local dealer ship on a 3 way call. Guess who I talked to:... yep same guy. I made an appointment for the next week. Dropped it off the night before. The day of the "proper diagnosis" I received a call from the same gal from GM wanting to know if I had been contacted by the dealer. I hadn't so she said she would call and call me back, which she did in 5 minutes saying she had good news. The ISS had been replaced for free. I thanked her graciously and later picked up the truck and thanked them also.
I later spoke with a coworker whose GMC also had the "clunk" and the dealer had fixed his with 160,000 miles on it.
Am I satisfied? Sure am it drives like the new truck it is, now.