Found a Michael O'Brien arriving Jun 1, 1836 from Ireland Age: 18 on the ship: Sylvanns Jenkins at Castle Garden Immigration Station Port of New York see link:
http://www.castlegarden.org/quick_search_detail.php?p_id=343... A link to the ship's manifest is below:
http://interactive.ancestry.com/7488/NYM237_30-0259/10224370...Michael O'Brien is on line: 45 and on Line: 46 is a Catherine O'Brien Age: 19 May be his sister or cousin.
Tim