Speedometer gear help!?!

I'm not sure if this question has already been answered for someone else, if so could you point me in the right direction.

I recently replaced the 904 trans in my 75 Duster after having it croak do to bad advice on kickdown linkage from some people! Anyway, I got the replacement 904 in and it runs great now, and my kickdown is set up properly now too! I used the same speedo cable and gear I had in the first one, because there wasnt one in the replacement trans. But now my speedometer will not work. It worked with the first transmission, it did jump around a little though, but I thought maybe that was do to the trans being shot. Did I put the speedo gear in wrong or what, I thought maybe there was a certain way you have to put it in because I noticed you can turn it and clamp it down at different spots? Can someone please help me figure this out? :angry7:

- Thank you.