Might be buying a 1983 Berlinetta on Monday. Only real issues, at the moment, are that the speedometer and odometer do not work. The speedometer is the mechanical one, not the digital. All other gauges work fine.

The odometer stopped at 64,000 miles, so true mileage is unknown.

Thoughts and possible causes?

 

the speedo drive cable has twisted off-this is fairly common on 82-83 that still used the old speedo cable driven 1970s type cruise control that gets dry bushings,binds and chatters,twists the cable.Start checking at speedo gear on tranny and work toward the speedo If cable twisted between tranny and cruise,oil the cruise control so it turns freely again.