1984 CHP speedometer cluster not working

[1BadAss5.0]

The 84 in question was verified through the VIN registry as being unit 2748.
With the purchase, the previous owner gave me The ford owner card that showed the in service date, E plate number: E862748, and other details. I pulled the driver side rear quarter and found the build sheet. That was a cool feeling, knowing this unit has passed through many hands and I was the lucky one to discover it. However, thanks again Bill for responding and giving a starting point with the speedo cluster. I will try to post pics but my iPhone does seem to be compatible with upload photos on this is site. Think I have to consult with my IT buddy on this as I'm a little slow in this area.