OK, I couldn't wait until tomorrow. I went to my shop and checked those things and took a couple more pics. There is a small set screw on this side of the shifter, but none on the other side. This side is for the 2nd-3rd gear shifter fork. But both of the fork rods do have detents in them. The larger fork measures 2-7/8" inside, but it doesn't have the 91A number or any number on it. And the tower doesn't have the 81A (or any number) cast into it. So is this an earlier shifter? Do I need to find the correct one?