sometimes it's as little as a different light on an electric machine. Some are more significant, like the updated bobbin winder, or the back tack feature.
I have my list showing
66
66-1
66-6
66-8
66-14
66-16
66-18
66-24
Singer did not produce these sequentially - and many variations were produced during the same time frame as one may have been a treadle, and another an electric version.
Unfortunately I don't have what the differences are on my list. Often the best way is to get a manual and look through for what is different from the others. However sometimes Singer made changes so the manual was updated but the model number didn't change. I've not checked the mechanics to see if there are significant changes that way, that would not show in the manual.
Last edited by Macybaby; 02-12-2017 at 06:19 AM.