roof

I am looking specifically to remove the vinyl roof off of a 1991 Imperial and swap it with one from the scrap yard but how is one secured to the car? I would hate to be traveling down the interstate and have my vinyl roof come flying off and potentially casing an accident, any info would help.

96-00 Sebring convertible. Has anyone else seen this? A rust trail down from speedometer needle... I'm hoping it's a common occurrence that just happens for no reason. 2nd best option is a side effect from being rained in once or twice. Worst case & my fear is submersion flood damage (which...