You obtained a hybrid VA tombstone. Confederate upright stones are to have pointed tops where Union stones are rounded. Furthermore, only the soldiers name is arched, followed by abbreviated military organization and dates of birth and death. No additional items can be inscribed.

Of note, his military records spell his name as Durdan.

…………

William J. Durdan, 4th Sergeant, Capt. John T. Bean’s Company,
13th Regiment Texas Mounted Vols.*
Enlisted March 1, 1862 at Woodville by Capt. Bean for 12 months
Elected 4th Sergeant May 26, 1862
Recorded as absent, sick in Convalescent Camp at Little Rock at end of year 1862
Taken sick on the march and sent to a private house**
Present at Jan/Feb, 1863 muster - In camp near Pine Bluff, Ark.
No further records [There are no further Company K 1863 muster rolls found in these records]

* This company was subsequently designated as Company K, 13th Regiment Texas Cavalry.
(Burnett’s Regiment)

** Note, 10 of the 12 cards in his file record his surname as Durdan, however, a handwritten voucher for commutation of rations for 14 days, February 11, 1863, is recorded and signed
W. J. Durdin

Compiled Service Records of Confederate Soldiers Who Served in Organizations from the State of Texas