Annoying Speedometer Noise at Cluster

I had one on a previous Demon that did the same thing. New speedo later and a new cable and it still jumped. (I never drove the speed limit anyhow) It turned out my speed odometer gear in the trans tail shaft was indexed wrong. The gear was actually toasted. I changed it and the housing and the jumping went away. Just saying that's what was my delima. It does not sound logical but it was the answer for me.
Good luck,
Joe