I recently installed a Locofi 3 in my diesel locomotive that has dual headlights. I wired the lights in parallel. The lights seem very bright, is a resistor recommended?
When installing LEDs in steam locomotive headlights, front and rear, check into color and lumens emitted. You don't want a bright white color LED in a steam locomotive or a transition era diesel locomotive.
If you're worried about burning them out, then there's nothing to worry about. If you simply want to lower the brightness, you may try an additional resistor of around 100 ohms in series to the parallel LED combination to see if that helps. By the way, wiring the LEDs in parallel is how it should have been wired.