If you mean the lower bed, back in 94 Ford still put the fold down rear seat in vans that was full length (side to side). This continued in the Chateaus until the late 90's. I'm just about sure this is one of those and the pic that looks more like a mattress is just the couch folded down with some sort of topper on it. It's either that or they remove the bench and set up the bed, which I doubt because they are super heavy.
There is a small bed above the rear seats and it looks like its a fixed size. I believe other Adventurewagen builds have top beds that slide out to make a large bed platform similar to the VW westfalias and eurovan campers. It's been a while since I have seen a Ford based adventurewagen for sale.
Too bad its a sliding door or I may be all over this one.