Josiah Rucks-Rev War Patriot

My GGG Grandfather Josiah Rucks, born in Chesterfield Co., VA in 1759 and died and buried in Smith Co., TN in 1836, fought with two of his brothers in the American Revolutionary War. He was given title to land in Smith Co., TN where he settled and formed a Baptist Church at Knob Springs. He is buried on what was his estate at Smith Co., TN. His headstone reads "A Rev War Soldier". At one time the DAR accepted this as proof of his service, but this is no longer true. I have been trying to find his service record or any other form of proof that he served. Does anyone have any suggestions as to where I might continue my search for this proof?