I am not aware of a buttonholer that fits a 66 back clamp machine, but I'm not sure that means they don't exist. I just haven't seen one. The back clamp feet are harder to find. It took me a couple of years to find the basic feet for mine. You can change out the needle bar so it will fit low shank attachments, but I was not sure how and wanted to keep mine as it was manufactured. You might want to ask the same question over at
www.victoriansweatshop.com.