Mike, the 20th Arkansas was composed of five companies from southwest Arkansas (Hempstead and Lafayette), and five from other parts of the state (Bradley, Hot Spring, Perry, Pulaski). Company K was organized on March 6, 1862, at Bright Star, Lafayette County, Arkansas. John S. Waldroup [Waldrop] was a member of this company. His age and residence matche the John S. Waldrop you asked about.