There are three different service files from Alabama for soldiers named Julian Nail. The man you have in mind joined Co D, 1st Alabama Cavalry Regiment, May 20, 1864, and mustered on June 16, 1864. He was absent on recruiting service after July 31, 1864.
His son Julian Nail (born 1847) formed part of a Jefferson County contigent who enlisted in Co. "A", 7th Alabama Cavalry, June 15, 1863. He left the company on July 1, 1863, and never returned.
You also asked about Julian Nail, 1st Sgt of Co C, Hardie's Alabama Cavalry Battalion. The physical descriptions and ages given for the two men are different. This man gave his age as 45, but may have been older. The census of Truss District, Jefferson County AL, lists him in 1860 as age 45. Trussville is quite some distance from Kendallville when your Julian Nail lived.
Apparently the Nail home has been removed to Tannehill State Park.