Since you have not taken it apart yet, I think that you might be getting a bit ahead of yourself.

On the SD, there is a plastic sliding piece that allows the arm of the regulator to drive the window up and down. This plastic piece fractures with time and is replaceable for about $2.00 or so. I cannot tell you if the 123 is identical, however, you might save yourself a bit of money if you do not purchase a bunch of parts, in advance.