My father recently came into possession of this clearly vintage sewing machine by "Singer Manufacturing Co".
I am looking into more information on it.
From one website I am told as the result of taking an identification questionnaire (since it is before 1958 or so when they started putting the model #'s on machines) that it is a 99-13.
However, looking up the serial number, I get multiple sources saying it is a 99k from 1951, with one source even giving a month and day of February 22nd (that source being IMSAC or however you spell it).
I e-mailed the gentleman who runs the first website I used with this information, and asked if he could help me figure it out once and for all. Obviously still waiting on a reply as I just sent it 5 minutes ago.
(my dad was a tailor as one of his many professions in his younger years, which also included coal mining, and literally being a grave digger).
However, here's the best part. Photos.