See also: http://www.rootsweb.ancestry.com/~arcivwar/tenthar.htm
J. M. McClure, 1st Lieutenant, Harman's Company D. Witt's 10th Arkansas Cavalry, surrendered with the Army of the Northern Sub-District of Arkasas May 11, 1865 under the command of BGen. M. Jeff. Thompson, paroled at Jacksonport, Arkansas, June 5, 1865, Description: enlisted at Clinton, age 24, blue eyes, dark hair, fair complexion, 5' 8", born in Ala[?, Could be Ark.]
T. H. B. McClure, Private, Harman's Company D, Witt's Regiment, 10th Arkansas Cavalry, surrendered May 11, 1865 and paroled at Jacksonport, Arkansas, Description: enlisted at Clinton, age 18, blue eyes, dark hair, fair complextion, 5' 5", born in Ala[?]
Witt's Regiment Arkansas Cavalry (See OR Series I, Vols 41 & 48) formed in 1864 by the consolidation of remnents of the 10th Arkansas Infantry and various other organizations in that ?? Dept., H. R Will, Col.
M317: Compiled Service Records of Confederate Soldiers Who Served in Organizations from the State of Arkansas
Note: There were no surviving regimental or company muster rolls for this regiment found in the Compiled Service Records. Neither man appears in the roster for the 10th Arkansas Infantry
I have lost my subscription to Ancestry.com, but have been able to get this much information from the 1860 Federal Census, which may be your men:
James McClure, b. 1838, resident of Prairie, Arkansas, Hamilton Post Office
Thomas B. McClure, b. 1843, resident of Yell, Arkansas, Dardanelle, Post Office