[Tundra2006CP]

The 06 Double-cabs come with the entire back window opening or closing vertically. You probably saw a factory window. I am not sure how early they started doing it - I am guessing 05. The new 07 CrewMax has the same thing. As far as I know it is not an option for any other Tundra - must come standard as the back interior wall is designed for it. I must say as an owner of one it is one of my favorite features. The entire window also has a defroster in it as well. The only downfall is during the fall alot of leaves that fall in the back of the truck will come swirling in if you don't wait for them to blow out. (same goes for rain rolling off the roof - it will blow in) Other than that it is a fabulous way to get some air without getting blown around or drowned out in noise. Hope that helps.