Roster of Confederate Soldiers, 1861-1865, confirms:

Heffington, Morgan AR 4th Inf. Co.C Cpl.

and shows the following other HEFFINGTON's of AR:

Heffington, B.B. AR 36th Inf. Co.I
Heffington, Charles AR Reeves' Cav. Co.A
Heffington, E.E. AR 7th Inf. Co.B 1st Sgt.
Heffington, E.J. AR 36th Inf. Co.I
Heffington, H. AR 36th Inf. Co.I
Heffington, J. AR 8th Inf. New Co.E
Heffington, W.D. AR 36th Inf. Co.I Sgt.
Heffington, W.F. AR 36th Inf. Co.I
Heffington, William J. AR 17th (Lemoyne's) Inf. Co.F 1st Sgt.