Seats have stickers but most fall off, loom labels too. Plastics have a date code system of dots - each time a month passes by they hit another notch in the mould - resulting in an extra dimple in the grid or circle pattern that you see.

I was surprised to discover that even my inlet manifold was marked up to match the head and engine number etc. on the rs500. I am guessing that wasn't the case on 3 doors and can't see anything on my saf???