I did the same thing a couple years ago. Mine was two of the panels only...the curbside top curved corner and the center panel. it was $3,400 at the mothership. There are no ribs up there above the window until you get to a bow at the white roof/end cap interface.
edit: There are no ribs nor inner skin IF you have cabinets up there. If you have inner skin showing, there probably are ribs.
"If the women don't find you handsome, they should at least find you handy." - Red Green