I have an 04; same truck basically. Low miles also, maybe 130k.
There's nothing unique about them that makes them much different from any other GM truck. The Z71 stickers on mine are even still intact so that's gotta be worth something. The main thing that the Av (and the Escalade that's the same thing) have that's any different, is the gaskets around the rear window and the wall behind the rear seat. Check that over carefully.
Z71 on that model truck in that year, incidentally, is nothing but the shocks they used, the addition of skid plates, and of course, the all-important STICKERS!!!! There's basically nothing functional about it, nothing that makes it "special"; no drivetrain or suspension differences besides the shocks (which are TOTALLY wore out anyway, since it has over 40,000 miles on it). Not worth wasting Internet bandwidth on. About the only thing it means is, that it probably isn't a "bottom of the line" truck, since generally the REAL bottom-feeders didn't even get that little bit of nothing. SO even though you see goobs on here all the time that think that their "Z71" needs "timing" or some other random thing different from any other truck, it ain't so.