The pension index shows Joseph F. Phelps, Co. A., 8th Mo Cavalry filed for a pension 23 Nov 1864, application 55548, and was awarded certificate 39823. On 30 Jan 1870 he married Sarah M. Gann in Dallas Co. and they are there in the 1870 census. I don't find them later so he may have died 1870s, which would be reflected in his pension file.