Dynamically changing posts?

Is it possible to manipulate the content of a post as its called by the loop (or a single page request) ? e.g. lets say I want to create a page that displays four divs, and styles each one appropriately. Do I need to add the class or ids to the divs when I enter them into the post or can I add the classes as the post content is called by the loop? i.e. can I set up a template that says “Place the first div from the post here and the second one there”?