X20.....The early built cars had the fully automatic antenna. turning the radio on with the ignition switch on caused the antenna to rise about 30-35 inches. Turning the car or radio off fully retracted the antenna to about 3-4 inches. The dash switch was, as Don points out, only used to raise the antenna higher than the automatic setting. It was only a 2poll spring loaded rotary switch. To determine if you have this antenna look at the body itself. It would have three wires coming from it (black white and orange). The manual electric antenna is solely controlled by the driver when the ignition is on. That switch is a 3poll spring loaded rotary switch. Both of those type switches are easy to find at most electronics stores. You will probably have to modify the stem to fit the knob, but that isn't beyond the realm of us hackers.
If I find the date of switchover, in my Service Craftsman News, I'll post it here......John
Don, good to see you back. A little slow right now.