Whenever i turn left i hear a knocking louder than normal when hitting bumps in the road. Even the smallest bumps. I can feel this knocking also in the steering. Is this just a gmc thing or should I go get my truck looked at?
Any kind of info would help.
Thanks again.

Your truck is covered under a 3 year 36000 mile warranty.
Take it back to the dealer and have them reference technical bulletin #00-02-35-003B
It is a procedure for lubercating the intermediate shaft. I have had great sucess with this procedure.

im over the 36,000 mile mark. Could i still take it back and get them to do it with out cost to me?

HAVE THE SAME PROBLEM, BUT ITS GETTING WORSE AND WORSE, TOOK IT TO THE DEALER, NO WARRANTY, THEY SAID FIRST LUBRICATE IF NOT CHANGE SHAFT, BUT IF THE LUBRICATION DOES NOT WORK I WILL HAVE TO PAY FOR IT AND THEN TRY CHANGING THE SHAFT AND PAY AGAIN, MY QUESTION IS ANYONE THAT HAS HAD THIS PROBLEM IT KEEPS GETTING WORSE AND WORSE OR IS IT THE SAME LEVEL OF "CLUNK"? WHAT DO YOU THINK I SHOULD DO? READ SOMETHIN ABOUT THE STEERING BOX GEARING CHANGED HERE IT IS;
I had this service done to my clunking '02 several times, to no avail. It became a real problem to get a dealer to believe it was something else, they all insisted this had to be it. The shaft got replaced once or twice, too. Didn't help a bit.

Finally had the steering box bearing changed. At the time there was no TSB for this procedure but people were talking about it on TDP and I managed to talk my dealer into trying it. Problem solved. It's now 40K miles later and still fixed.

Just a heads-up that there's more than one possible source for a steering column rattle

HAVE THE SAME PROBLEM, BUT ITS GETTING WORSE AND WORSE, TOOK IT TO THE DEALER, NO WARRANTY, THEY SAID FIRST LUBRICATE IF NOT CHANGE SHAFT, BUT IF THE LUBRICATION DOES NOT WORK I WILL HAVE TO PAY FOR IT AND THEN TRY CHANGING THE SHAFT AND PAY AGAIN, MY QUESTION IS ANYONE THAT HAS HAD THIS PROBLEM IT KEEPS GETTING WORSE AND WORSE OR IS IT THE SAME LEVEL OF "CLUNK"? WHAT DO YOU THINK I SHOULD DO? READ SOMETHIN ABOUT THE STEERING BOX GEARING CHANGED HERE IT IS;
I had this service done to my clunking '02 several times, to no avail. It became a real problem to get a dealer to believe it was something else, they all insisted this had to be it. The shaft got replaced once or twice, too. Didn't help a bit.

Finally had the steering box bearing changed. At the time there was no TSB for this procedure but people were talking about it on TDP and I managed to talk my dealer into trying it. Problem solved. It's now 40K miles later and still fixed.

Just a heads-up that there's more than one possible source for a steering column rattle

This is true..there could be more than one cause of a noise in the steering system...probally 90% of clunking noise in these model trucks is caused by the steering shaft...if the shaft lube procedure is done and the vehicle properly road tested after the repair, the technician should be able to detect if the vehicle was repaired or needs further diagnostics before the customer picks up their vehicle

Thanks for those who have written about this. I took my '03 Sierra in yesterday to get the tail gate cables replaced (under recall) and mentioned this clunking to them. Since it's still under the warranty, they ordered the part and will send me a post card when it comes in. Apparently this is a big problem and they are low on stock of these parts.

Thanks again!!
Rosscoe

My 03 Sierra is beginning to have this problem but I still have 2 years to go on the warranty. Glad to know I'm not hearing things.