Yeah, but sometimes there are ways to get them to go flat, I just don't have enough experience with the 2006 to know. Some of the seats in the 80's would have two different levels to pull the level up. Pull it up 3/4 of the way and you can go back 3/4 of the way, pull it up all the way and you get to go back flat.
However, don't force it. Why do you want to go flat anyhow?

Plan on sleeping in the truck?