Rear Pillar speakers 2001 Yukon XL

I have a 2001 Yukon XL SLE and while checking out the speakers to decide on replacement options I found the rear pillar speakers. They are little 3" speakers. Everyone I've asked at stereo shops think I'm crazy when I describe them because they don't have it listed as being in the car at all. It looks to me like it's stock. Anyone familiar and what did you replace them with? So far the 3" I've looked at are too deep.

Don't know about that, but did you place any woofers in the front? The 2001 Yukon Xl is weak for front seat bass.