When I got my Suburban I found out about the 06 Suburban LTZ. It's basically a unicorn. They are pretty rare. They basically came with Z71 trim, but all the plastics were black instead of gray. The roof rack and step bars also look exactly like the Z71 versions, except they are chrome instead of black. Then the grill is somewhat special as well, it's a color matched grill just like a Z71 grill, but then just the center bar is chrome like the 99-02 Silverado grill. Then GM also decided to throw in the Escalade door handles and the same exact 20" chrome wheels that came on the Silverado SS. And don't forget the drivetrain, it had an AWD 6.0 just like the Escalade and Denali.
It's like GM took all the best parts off the GMT800's and put them all on one SUV for the final year of the body style.
I remember when I bought my black Suburban LTZ front air dam. I searched high and low and I couldn't find one, all I kept coming up with was the gray Z71 air dam. I ended up getting a VIN from a 06 LTZ and then using that to get an actual part number from the dealer. Once I had the CORRECT part number for the actual black air dam, I tracked one down that a Chevy dealership was selling on eBay. Now you can find aftermarket black Z71/LTZ style air dams all over, even at Rockauto.