According to the Kaiser-Willys Sales Corporation Trade Letters I have in hand on the ordering information for the Darrin, windshield washer was not a factory-installed accessory. According to the Kaiser-Darrin parts book from the factory issued May 1954, only the following items were available as dealer installed accessories for the car:
Heater/Air Conditioner
Wire Wheels
Safety Belt
Exhaust Deflector
Why don't you ask the Darrin Registry Manager or Lee Abrams about this?