Susan, you should go to the Civil War Soldiers & Sailors System online at www.itd.nps.gov/cwss/soldiers. Type in your soldiers name & state from which he served & it will tell you if a record exists for him & what regiment he served in.
My gr-grandfather was in the 8th Missouri Cavalry & at the wars end many of the men were transfered to the 11th Mo. My ancestor finished his service in Co.D of the 11th Mo. Its possible your man was also from the 8th. Email me if you have anymore questions...dave