Thanks for all the input. Per JimD & Chris Obert, all radios were dealer (or after) installed, so likelihood of factory switch availability is probably quite low, in the U.S. anyway. However, since there IS a connector in the harness, like the hazard switch connector (not a generic connector, but one apparently designed for Fiat switches), there is still a chance. I have contacted the guy in Italy with the switch that Erwin referenced above and am waiting for a response as to the measurements. It looks hopeful. It has the "socket" for the fiber optic "fitting", and the Ritmo/Strada is in the same year bracket as the X1/9.
We already have a stereo/CD changer (I know.....obsolete technology now) for the car. I will try to check out whether it's antenna output works only for the radio, or in any mode. I am pretty sure that our Honda radios send the antenna up, even when playing a tape.
The window switch would likely work, but if we can get the correct symbol on the switch, we would prefer that and the Ritmo switch is closer in overall appearance to the other Fiat switches in the console.
Dr. Jeff....Our 79 has been apart for many years as well. I had never noticed the connector & the wiring until a few days ago. I will be interested in what you find on yours.
I know that most folks would just use a fully automatic antenna and a stereo that takes a flash drive, but......