DOB 19 MAR 1829 YEAR IN QUESTION LONDONDERRY TO US ABT 1845
Do you have any idea what county he was from? Did it appear in any U.S. records such as death, obituary, headstone, marriage, children's birth records, even censuses? Knowing the county would help narrow down the search in the Irish records. Also, there are no Irish birth records for the 1830s...only baptismal records...so they would likely include baptismal date not birth date.