Joe:
Without more information on your family, we can't tell you the parish. In the mid-19th century the surname Dunlevy was found primarily in Co. Mayo and Co. Donegal. The more common surname, Dunleavy, was found mostly in Mayo, Donegal and Sligo.
See http://www.irishtimes.com/ancestor/surname/
Can you provide more information on your family and when they left Ireland?
Roger McDonnell