There is also a W.D. Fuller in Bourland's Regt at the same time and also absent driving beeves. This may be your William D. and his father J. Fowler in Bourland's regiment in late '64-'65.

By the way, if you aren't aware of this, Ft Washita "C.N." is "Chickasaw Nation", located between present Durant and Tishomingo OK.