Hi, I picked up a 158.904 Kenmore like yours at an estate sale two blocks from my house about a month ago. It is in a decent-shape, large size cabinet and came complete with manual, cams, buttonholer, attachments, and even a circular decorator by Kenmore. It is the pretty cream and lavender shown in your photo, but mine has a couple of scratches on it and is missing the decorative lavender center disks glued to the center of the stitch length dial and the reverse button. Otherwise, it is in good shape. If I can figure out how to post a .pdf of the manual, I will.
Mine may be a little different from yours in that it is definitely a high shank, class 15 machine. I am having a bit of a problem adjusting the tension, so it probably needs a more extensive cleaning to get the tension correct.
I had thought about giving it to a good friend's married daughter who is a novice sewer but appears eager to learn. This may be too much machine for her due to operational complexity concerns expressed earlier and I have a bunch of easier to use machines one of which I may consider giving her. I would appreciate anyone's thoughts on that point.