Posted in recent purchase but saved the explanation I believe it is the 1968 Sears Kenmore. I have been having a lot of problems with the sewing machines I normally use. They are both rather on the light duty side of a machine. They work but I have been doing a lot more heavy duty sewing recently. Those machines have been suffering... So I located this machine at a thrift store for about $15 including tax and then about another $4 or $5 for a generic belt. I tested it out and it is a BEAST! Perfect spacing and zig zag pattern. Tested through multiple layers of duck canvas. Ultimate test was to double the canvas over 5x making it 10 layers thick. The machine with 10 layers of duck canvas performed perfect through all the different stitches In comparison the other machines I use start to have problems around 3 layers..
