Just a quick note for folks who may run into this. SharePoint allows you to create information management policies on content types, and then those policies will apply to all instances of that content type regardless of where they live. To add a policy to the content type, go to Site Settings –>Site Content Types –>Click on the content type –> Under the Settings heading, click the link for Information management policy settings.
If that link isn’t there, go back to Site Settings and go into Site Collection Features and activate the Library and Folder Based Retention Feature. Not exactly obvious since it doesn’t refer to content types, but that’s the one you want. Once that Feature is activated, you’ll see the Information management policy settings link in the settings page for the content type.