Hugh,
There are some pictures on the Illinois in the Civil War website and in those pics there are three of CSA men. One is Mr. Holt and the other two are unidentified. The last two have different uniforms that Holt does. The jacket is down to the waist but it appears in the photo to be heavy wool to me. Maybe that is the uniform we are speaking of. Just a guess. Have no idea what the origional uniform looked like. If one exists today, I am guessing that it might be at the Illinois National Guard Military Museum, but again just a guess.
Frank