My latest research in post
Wiper Switches - take 5?
It appears that cars until 1966 (or 65) offered only single-speed or variable-speed. Later cars offered only 2-spd or 3-spd using resistors on the motor (now in engine bay). The washer push-button function was optional. You have a "W" terminal to a tan wire which routes into the engine bay if the option. All premium switches (variable or 3-spd) might have had the "W" option. Of course a switch with "W" can be used with no-washer wiring, or you can run a wire yourself to engine bay (I did), preferably using an open bulkhead position. Pretty sure my 1969 Dart "Custom" didn't have the "W" option since it had the "rubber bulb - foot pump washer".
