GM used to advise that this part just be lubricated in order to solve the notorious steering shaft clunk.
I even bought the GM "kit" which included a tube a grease, some sort of special clip, and a D shaped rubber plug with a wingnut on it to get it VERY tight on the steering shaft. The plug was to hold one end COMPLETELY sealed as you forced the grease into the other end. I ended up greasing mine TWICE. I kept the kit and just bought more grease the second time. Each time I regreased it I was lucky to get about 6-8months of quiet clunk free steering until the clunks returned. About the time I was getting ready to take it off and grease it up a third time, that's when I heard that GM redesigned the steering shaft to a new "greaseless" design. So I bought one of those. Actually, I got one and got it installed for free because of my extended warranty. They didn't want to cover it at first because GM said that it just needed to be greased, so it was considered a "maintenance issue". But once GM changed the part design, then it was technically a failed part that needed to be replaced, and then that had to be covered under the terms of my warranty. But anyways, that "new" steering shaft failed miserably in about three months. I honestly don't know if it was even replaced, or if they just regreased mine and told me they installed a new one. But then once that one failed they definitely installed a new one and that one has actually been COMPLETELY clunk free for the last 9-10 years or however long it's been on there.