BTW- just about any Singer set (green box) will fit your machine - just make sure it's short shank. They are more common on eBay than the black box greist sets. By the time Greist switched to the cardboard box, they were making many side clamp sets similar to the one on the right. If you get that style, make sure the adapter part is included.
This is what the set that would have come with my 1955 221 would look like - and yes, at this time there were often a mixture of black and nickel finished pieces. If you look in your manual - you'll see pictures of the basic attachment set that would have come with the machine.
