Charles
You may want to look at Record of service of Michigan Volunteers in the Civil War 1861 - 1865 A.K.A. Michigan Brown Vol. 45. Three companies of Merrill Horse were recruited in Michigan. The book includes a full roster of the men recruited in Michigan, along with each man service records, it was not uncommon for Michigan boys to enlist in Ohio regiments and vice versa to occur with the Ohio enlistee in Michigan regiments the majority of swapping happen close to the southern border of the state or for those enlisting in Michigan regiments the northern border of Ohio and Indiana. You can find the book on Ancestry.com
Marty