Pull up on the speedo cable at the trans. See if the clip popped out. The cable may not be sitting all the way in the tranny if the clip has popped away. If you checked your cable, you may not have installed it back right. And also,if you take the cable out of the trans, and pull the thing, your speedo should move. If so, it's something inside the tranny that broke. That is, if your cable is o.k. and it's installed right into the tranny. My bet would be your cable popped out of the tranny. I've never heard of a speedo cable breaking. I've heard one squeak, but never seen one break.