Sharon, this is all that I could find in my Thackston files.
I found a Alexander Thackston, born 1846 in Prince Edward County, Va. The son of John Thackston, born in 1788 in Price Edward County VA, and Martha Dabbs. Nothing more on Alexander.
I also found an Alexander Thackston born July 1848 in Mason County, Ky and died 26 July 1900 in Mason County, Ky. He was the son of John H Thackston, born 1793 in Prince Edward County Va. and Minivera McCready. No other information of this Alexander as well.