'64 dart amp gage

Could be shorted rectifier, doesn't happen often, but does sometimes.
How far does the meter go into D with ignition turned on and motor not running, let's say, compared to headlights on with ignition off?

Had to resolder on the button for the rear right turn signal lamp socket, musta taken 20 minutes! Darn these 50 year old cars anyway and repairs that cost nothing but a little TLC.