Duster Sail Panel Installation

Its been about 2 years since i removed the plastic sail panel pieces from the duster, and i can't remember if the back edge tucks under the gasket for the back glass (like the headliner) or rests on the outside? It looks like it should tuck in there but when i tried it didn't want to go far enough for the screw holes to line up, and i really don't want to break these brittle plastic pieces trying to install them. Thanks for any input guys!