Nancy, here is more info for you on the 66's. I have two 66 machines dated 1921 and one has the back clamp and the other has the side clamp. The one with the side clamp came with an add on stitch length reg. If you remember when I posted a picture of the machine we all wanted to know what that ugly thing was on the front of the machine. I also have a 66 dated 1916 with back clamp. I have another 66 dated 1919 and it has a back clamp. Then I have a Lotus and it has a back clamp dated 1910. Add these to your list so we can keep up with all the dates.