mendymom,
To a certain point yes. The 66-1 is the updated machine that has a motor boss on the pillar. The 66 does not have that.
The back clamp feet were used up till the 20s I believe when they switched to the side clamp ( low shank ) style. That model number I believe was the 66-4.
From what I've seen many if not most of the 66-1s have been updated to the side clamp presser foot shafts. I have two like that. A treadle and a rebuild.
There is a list on ISMACS, here is the page the 66s are on. Much of this information is there.
{
http://www.ismacs.net/singer_sewing_...sses-1-99.html }
Joe