my sheehan origins in ireland

[msheehan]

Hello, 

Trying in vain to track down where in Ireland my great, great grandfather Michael Sheehan (DOB 9/25/1840) was born.  Parents:  Michael Sheehan and Mary McNamara.  They immigrated to Ontario Canada in about 1847-1848.  I found baptismal records for Michael's 4 brothers in Mill Creek, Ontario in 1849, 1850, 1853 and 1854.  They were in Mankato, MN by 1862.  Michael married Margaret Dixon in 1868.  He died in 1923.  Extensive search of Roots Ireland, Ancestry.com, Family Search etc. has not been fruitful.  There are several different references as to birthplace in several family trees on Ancestry but none of them has any PROOF such as a baptismal record that I can find.  Any help would be much appreciated.

Mike