[TABLE]
[TR]
[TD]G-
[/TD]
[TD] 6413646
[/TD]
[TD] 6463645
[/TD]
[TD] 66
[/TD]
[TD] 50000
[/TD]
[TD] September 17 [/TD]
[TD] 1918
[/TD]
[/TR]
[/TABLE]
From the Ismacs link posted above:
So that means that the machine you have is a model 66, one of 50,000 whose serial numbers were allocated on September 17, 1918. Therefore, I bet it has a round bobbin, located to the left of the needle.
To post a pic, click on the picture frame above the window you're responding in (to the right the 2 "globes" and the left of the film strip) and it will let you find the picture on your computer. Browse to it, pick it, and let us see your lovely 66.