http://www.singerco.com/support/serial_2letter.html
I am not sure what the letters are to connect you to the right series... AF series is this
http://www.singerco.com/pdf/SINGER_AF_nos.pdf
and if the number is AF103268 it was made Nove 21 1938 but not sure ... you need to look closer into the numbers embossed on your machine.