When I was setting up the lights on the 41 pickup I discovered a type of bulb I hadn't even seen before. They are ideal for converting an existing park light to turn signals. You never know, this little tip just might help somebody doing the same job.
If looking for these look for ba9s and then look for amber and 23W. (not 21W as I say).
Mart
https://youtu.be/wBlORE5fXdI