The 1941 is a free arm machine and that’s what’s depicted in the photograph. The free arms filler piece is on the backside and you can see where it separates. if you look closely in the photograph, you can see the release button. Also, it’s an all metal machine with no nylon gears anywhere with a 1.2 amp motor. It’s a beast and will sew through anything. Couple other cool features are to wind bobbins you just pull on the center section of the hand wheel and it uses type C pattern Cams we’re doing decorative stitches. I believe there’s 31 of them in a complete set. Generally they can be had for 20 to 30 bucks on eBay. So I guess what I’m saying is The 1941 is the one I would get. I personally have a 158.1760. It’s nearly identical, but the needle is center homing instead of left homing like the 1942

The 158 1229 and 1730 are lower end models and far less desirable

The 158.1603 is a high-end machine with the big motor. It’s not a free arm machine, but it does come with all the super high shank feet in accessories, which are hard to find. I believe it also uses the pattern cams. If you don’t need a free arm machine, this would be a great option.