Mine is 116851, if my memory and research are correct this corresponds to Oct 1941. Based on chart your serial falls in 1940.
http://wiki.vintagemachinery.org/South-Bend-Lathe-Works.ashxPS considering selling 116851 to the right home, so curious as to what you were willing to give for a 1940 era 9 inch Southbend.
Len.