The 66/67 console base is plastic, so it can't ground through that... The clocks have a tab/ spade (electrical connector) welded to the clock body where the ground wire goes... That wire is in turn attached to the floor bracket for the console with a special connector, kind of slender "C" shaped (like a sheet-metal J-nut), that slides over the metal of the bracket, with "teeth" on the inside to grip the floor bracket...
If the clock is missing the connector, you could always use some ring connectors... Put one under one of the sthat attach the clock to the console (as long as it is touching the metal clock housing), and run the other end to the console bracket on the floor... You could also use a ring connector here...
If the clock is missing the connector, you could always use some ring connectors... Put one under one of the sthat attach the clock to the console (as long as it is touching the metal clock housing), and run the other end to the console bracket on the floor... You could also use a ring connector here...
