What year of Suburban is that out of? I've never seen one like that.
I want to say they started those in '95 but I'm not exactly sure... My '97 'burb has two of them, one for each row of rear seats.
There are two versions, one is a little taller than the other. In the 'burbs, the shorter fixture goes above the second row, and the taller one goes above the 3rd row.