On later Sprites and Midgets, there is a post that runs up the center of the windshield which secures the rear view mirror.
– The earlier cars (1967-1969) use a chrome center post which leads up through a mount for the mirror itself and secures to the top of the windshield using an upper mount.
– The later cars (1970-1980) use a silver painted center post which mounts on the dashboard and terminates in the mirror itself, mounted on the top of the windshield frame.

There are different versions, so be sure to get the correct one!