Your rear bumper is the same as mine on my '08 Suburban LTZ and I think mine was replaced by the previous owner because of this...
This area on your truck...
View attachment 203318
Should look like this on an LTZ...
View attachment 203319
It's a very subtle difference and hardly noticeable.
Also, it's hard to tell in the pic but, it doesn't look like you have backup sensors in the rear bumper.
My other suspicions for mine, and it looks like yours too, is the absence of the chrome strip along the black bumper pad and the fact that it doesn't have the place for the hitch cover.
I am still curious why yours has color matched side molding without the chrome at the top.
Beautiful Typhoon BTW... love those trucks... gonna own one someday.