Weedwoman,
The site is: www.singerco.com/support/serial_numbers.html
For some reason the hyperlink does not copy correctly for me...so you will need to cut and paste the site into your browser address bar....
Once you are at the site you will need to choose the option for your serial number (no letter, one letter, or two letter prefix), after you click on the option you want you will be taken to a page that has the links for the charts....on the right hand side of the page there are pages that can be downloaded to your computer so that you can look up the numbers without going online....each time I buy a machine with a new set of letter prefixes I download the chart for that particular set of letters so that I have it for reference.....
Darcene
Based on your serial number information we now know this:
G- 5335636 5385635 66 50000 April 26 1917
It was produced in the approximate middle of this production run...it is a model 66...this run was 50,000 machines allotted on April 26, 1917.....
In the charts the numbers start with the six digit numerals and as you work your way down the list you will come to the seven digit numerals....it took me a while to figure this one out....also, if you have a machine that starts with a leading zero....don't ignore the zero, just work your way down the chart until the number shows up with the leading zero included....