Rarest A-Body Option?

I've never seen the 110 mph speedo. But one of the most rare had to be the option of the upgraded interior light option. It had a light for the key to remain lighted for the driver to find the ignition after entering the car at night. These cars were not designed with a lot of creature comforts.
No doubt there are some like the Hemi that deserve the high praise but for common add on's, .