Scott,

There are several Union (and several southern) units from Caldwell County, MO (home of Kidder and Mirable)in which your ancestor may have served. He could even have served in more than one of them. I strongly recommend that you contact MO State Archives and get the specifics:
Missouri State Archives
State Information Center
P.O. Box 1747
Jefferson City, MO 65102

phone: 573-751-3280
Fax: 573-526-7333

E-mail: archref@sosmail.state.mo.us
or http://mosl.sos.state.mo.us/rec-man/arch.html

This process takes about three months but I am told it is free for descendants. This will take the guesswork out of the process for you. You may also obtain forms from your local library to ask for similar information from the National Archives and Records Administration in Washington, D. C., but they would not have all the local home guard material. I wouldn't want you to miss out on that since there is a good chance your ancestor served in the notorious "shoot first and ask questions later" 33rd Enrolled Missouri Militia from Caldwell and surrounding counties.

Bruce Nichols