Ruiz,
The "K" in the 99K indicates it was made in Clydebank (UK).
There is a tremendous amount of information on your machine in the ISMACS site:
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http://www.ismacs.net/home.html }
Including serial numbers, production quantities and dates for many many Singers as well as other machines.
If you look in the owners manual there is a section on accessories. Lots of accessories for that machine. It is a low shank machine and uses common Class 66 metal bobbins as well as the common 15x1 needles.
It's the 3/4 sized version of Singers Model 66 machine.
Joe