steering question

I have a 2000 Z71 4X4 I bought about a year ago @ approx 45K one owner. It has the 5.3 ( no engine noise) and runs great. My only problem with the truck recently is a rubbing feeling in the steering shaft. any idea's?

I have a '99 that had sort of a thumping as you turned. The dealer installed a grease kit that cost about $90 to fix. It is one of a long list of common problems.