They were phased out... kinda random-like. IE 1697 had a gas flap... but 1698 might not have... and the 1705 did again.. No exact end (BTW, those were just example vins... someone probably knows approx. when the gas flap went the way of the brontosaurus... I think pretty much the 82 model year was the approximate changing point). And the trunk was no different. The flat hoods have a little piece of carpet where the hole would've been... and the weather seal still wraps around the gas filler, instead of going straight across like might have made more sense. But since the plastic underside of the hood and the shape of hump in the underbody where the weather seal sealed stayed the same throughout production.... eh... I want a gas flap. And 1 million dollars. Feel free to donate either. good night! it's way too late. James L 04009