Really dumb question
 

I have a 2000 Silverado with the 4X4 shifter on the floor. I want to change the stock plain black plastic shift knob for an aftermarket woodgrain one like I have done on my last two trucks. Here is the problem, I can't figure how to get it off. The others just screwed off, this one won't. I didn't see any set screw either that might have been holding it on. Somebody help out this knucklehead! Please!