Russ, the 3-wire switches are for Hudsons that employ two lamps in each taillight. One of the lamps (a single filament) is dedicated to the turn signal, while the other lamp (a dual filament) serves as the taillight (the dimmer filament) and the brake light (the brighter filament).

Six-wire signal switches are for Hudsons with only one one lamp in each taillight. The lamp is a dual filament. The dimmer filament is the tail light. The brighter filament is the brake light. When the car has turn signals, the turn signal switch routes the circuits to the rear signals, through the brake light switch. Thus, if you're making a left turn the bright filament flashes, but if you put on the brakes it will still flash, while the bright filament in the right taillight will merely come on (as it would normally when you step on the brake).

The six-wire switches are handy for retro-fitting turnsignals onto Hudsons built before signals were available. and which have only one socket in the taillight.

Thanks, Jon. Very informative.

Jon,

A very clear, understandable explanation! Thank you.

Per