Jim:
There is a listing for a Pvt. George W MClewer in the Missouri SOS files for the 39th Regiment Infantry Volunteers, Co D, under Captain Meridith. Enlisted August 20 1864 Hannibal Missouri, Discharged July 19 1865 at Benton Barracks St. Louis, MO
The actual card image has McCleuer, Geo. W. This is a perfect match for your information.
http://www.sos.mo.gov/archives/soldiers/details.asp?id=S211074&conflict=Civil%20War&sType=unit&txtUnit=39th+Regiment+Infantry+Volunteers&selConflict=Civil+War&offset=600#
John R.