The A-X program started in 1966, but for turboprop. By May 1969 turbofans were specified. First flight 30 May 1972.
Su-25 design work started in 1968. First flight 22 February 1975.
So the two were designed at basically the same time!
As the previous post by johnbr on the Curtiss O-52 Owl, there's a Northrop A-9 on display at Castle Air Force museum just near Atwater, California. Yes, took dozens upon dozens of detailed photos of the A-9 there too.... :0)