Could be VSS, but my car did the exact same thing after I swapped the engine, and the random numbers would change with the engine's RPM. turned out to be a faulty ground.
Check your ground connections on the front of the engine by the bellhousing. If those are good, try unplugging and cleaning the VSS connector inside the passenger side wheel well, then plug it back in. If the problem is still there, try replacing the VSS, and if that doesn't fix it, you might have to replace the HUD.
Most electrical problems are caused by poor power/ground issues - when hooking up wires, remember this: clean and bright, nice and tight.
