Unless you get extremely lucky you're unlikely to find a manual with your model number on it. Most manuals for the clones are "generic"; that is, they won't have a name or model number on them because all the clones are basically the same no matter the manufacturer. The differences will be the color and the cosmetics of the stitch length lever. You have a beautiful Japanese made Free Westinghouse model 170. Probably imported at the tail end of the Free company's existence. Several American manufacturers did the same thing in the 50s and 60s, started importing Japanese machines when they stopped making them here in an effort to stay in business and compete with the ever growing popularity(and prices) of Japanese machines.
Cari