Thanks so much everyone! I did some more digging around, reading, and picture study last night. I now have a clear picture about back clamps vs side clamps (and could recognize them!), solid and spoked wheels, etc. Your information helped immensely. I am going to pass on the 66 for now. You all saved me a short road trip and who knows what else!
I feel like I know a lot about modern Berninas, but I am such a newbie on Singers and all the other vintage machines. I am just so fascinated! I learned to sew on my Mom's Japanese made White in the early 60's, received a Nelco for high school graduation but moved to Bernina in 1975. My mom still has the White sitting in my old bedroom closet and I will be picking it up on my next trip home.