Welcome ttist25, The 15 clones are generally a good machine. There is a thread here with lots of them -
http://www.quiltingboard.com/picture...p-t164361.html
You are correct that Great Eastern Equip. Corp did rebuild some early Singer machines as evidenced at this link
http://www.sil.si.edu/DigitalCollect.../sil10-204.pdf They probably later came to be importers of the Japanese machines. Yours
is a Japanese 15 clone.
You may find a JA and/or JC number on the bottom of the machine. They could be cast or stamped into the metal. If so the number after JA or JC might indicate the Japanese company that actually made the machine. However, there are some that are unknown as the Japanese records aren't very good.
That sure is a nice looking machine.
Janey - Neat people never make the exciting discoveries I do.