Speedo.

Hi, for the past few weeks, I've noticed my speedometer will work intermittenly (it works more times than not). Interestingly enough the odometer continues clicking off the miles just as if the speedo were working normally. When it fails the speedo just falls from where ever its at. Never at any time ralated to any other time that it fails as far as I can tell. The only things I can say I changed in the past few weeks are two radiator hoses(leaking, and split) and recently locking the ADD, while installing locking hubs. Its a '93 Toyota Extended Cab, Loaded, 3.0, SR5. I haven't cracked open the Chiltons yet for lack of time, but if anyone has any ideas I'm willing to read and learn about my new Toyota. Thanks for reading this post and any possible help.