Marking of rear bumpers

[pagode rob]

On both rear bumpers of my 250SL (1967)I found a marking-number and a marking-letter (see att. picture).
Does anybody knows what these marks mean   

Greetings,
Rob

[DaveB]

I don't know their significance but haven't seen them before on original bumpers. It may be a rechromers mark but in that case I would expect a consistent symbol (I'm sure you already thought of that).