Is yours the Syncro II for 7 speed, or the updated Syncro II that is 8 speed (sometimes called Syncro III and was the last version of Syncro). I thought there was some info on it at tearsforgears or velobase, but I just looked and didn't see it. I know when I was looking years ago, I found info somewhere. I did find the attached photo which might help, if you have these shifters.

The "Syncro III" looks a bit different than the Syncro II shown above, and I would imagine the small parts/installation are different too. The main distinguishing features in the "III"/updated one are a little micro-adjustment knob on the right shifter and the lack of the knurled knob on the right shifter - see second photo. When I installed mine years ago, IIRC, I was missing one of the little washer-looking parts, but was able to make do. These shifters work really well.