Hi John,
thanks for the reply, I found some photos of the restored #3 car (Red/White Gurney car) and this seems to have what appeared to be a light behind the recess. I reckoned this might have been of use as a night driver change aid. However Iguess a contrasting colour would work just as well as you say. The recesses seem to be separate parts that have been rivetted into the door skin rather than part of the original moulding so I guess final positioning could be even more varied than I 1st thought.
Thanks for the
info