Let users chose between predefined user titles

[BirdOPrey5]

You could modify the $vbulletin->userinfo['field7'] code to be in an if statement to only display for users of certain groups but off hand I don't know how you would stop user's from outside that group from choosing a title- you can just block it from showing. Maybe put in the description "This field will not affect users in x,y,z usergroups."