new member seeks possible answers?

Hello all. I am new to the board and would like info for a certain question. Has anyone ever converted a 2dr hardtop valiant or dart to a convertible? I've looked all over but couldnt find any info. I noticed rust bubbles under my vinyl top and removed it, to my surprise im wondering why my rear window hasnt fallen through yet. Any info will be greatly appreciated. Car in question is a 1972 Plymouth Valiant.