1983 Berlinetta 6-cylinder
 

Hello- new to group. Have a 1983 Berlinetta that my parents purchased new. Speedometer cable was squeaky so I pulled and lubed with graphite. That solved the problem. About a month later the brake booster that was original to the car failed. While nursing the car back home the speedometer quit working. Replaced the brake booster and brakes are good again. Speedometer still will not work. Now noticing the cruise control doesn’t work either. Checked dashed connections and cable and all are good. Any thoughts? Does cruise control failure impact speedometer operation as well? Thanks in advance for any expertise.

"Does cruise control failure impact speedometer operation as well?"
I think it may be the other way around, speedo failure probably causing cruise not to work.
Plastic drive gear in trans that turns the cable maybe failed?