alissa,
It is definately a Mdl 15. One of 25,000 allotted on 10-17-39. I can't say for sure what dash number it is, but it is a Mdl 15.
Labradorsmom,
The 201s have the tensioner on the front like the 66s and 99s. The Model 15s have the tensioner on the rear side of the face plate. It's the only machine Singer made with the tension in that position.
They are very similar but not the same.
Joe