Kenmore is a Badge name used by Sears, and Sears had them made by several different companies over the years, in this case the 158 prefix indicates the manufacturer, so if you have a Kenmore with a different prefix, it's made by a different company. BTW- Sears retired the Kenmore badge not that long ago, and started selling machines under the manufacturer's name.
I have a 158.18 something, I bought it specifically because it has a chain stitch adapter. I have a thing for machines that can do chain stitch along with regular stitching.