Yes, I'm aware of those Singers' 15. I have seen them before in my many google searches of vintage sewing machines. My point to Jenn, was to start her research with the fiddle base and then go from there since she didn't know that she had a Singer VS2. Wiki does a very good job of describing the differences. There is more to just the fiddle base in deciding what type of sewing machine. But I have an advantage at knowing that was a Singer VS2 since I own one.
Jenn, Enjoy that machine! The Singer VS2 produce beautiful stitches. Very nice machine!!!