Back in the day, it was not allowed to have a yellow amber turn signal it was "European." spec. cars that had it. I know this as I imported a car in the 80’s and was forced to remove the yellow lens on the BMW 3.0 CSI coupe.
When I got home into my 64 bug conv’t with the yellow european spec. Hella lenses on it I was truly a rebel and a rule breaker.
Some other European cars had parking lamps for when you parked Italian style on the sidewalk and hung a fender off the curb you could leave the tail or turn signal light on on that side only as a warning to other drivers.