Alright. We'll go with vault 5 for mine.<br/><br/>As for the idea for another vault, I figure number 80 can be one where the population was meant to attempt to achieve a form of eternal life through a sort of rebirth. All the female inhabitants have the ability to stretch s bit, giving them the ability to put humans in their womb, using a gestation period to essentially bring them to a younger age (unbirth, simply). The idea is they'll make the oldest members younger and so on as long as possible.