Here we are again ;-)
For those who couldn't see the "cuckoo", turn signal, on the roof at my Dad's Volvo (This link is not my dad's car. I found it on the Internet, but here you can see the turnsignal much better) from 1951. Here's the pictures again . The cuckoo is inside the red circle =)
I admit that it's very tiny, but its there. Sorry but I can't enlarge the pictures more because they are from a Super-8 film .
Have a nice day!