I will be quite interested to read about the Euro vs. US vs. Rest of world comments on stickers.
One of the bigger changes will be in relation to the US emission regulations (re the valve cover stickers, and other emission control devices on the US cars).
I believe there is a reasonable amount of variability on the locations of stickers, i.e., the trunk air pressure label. There was most likely not any type of centering device for the sticker, they just knew they needed to go in this general location. A friend of mine here in SoCal like to argue about these small little details. One of my favorite discussion points with him is the snowflake decal in the windshield. I have seen it by the driver side and also by the passenger side....
One point of note/curiosity - if you take a close look at the oil level sticker, the part number is printed on the sticker. It begins with "114" which usually indicates the body type. The 114 cars were produced beginning in 1968. If that body number item is accurate, the sticker would not be on a 230 SL and probably only a very late 250 SL (if any)....??
Authentic Classics gives some guideline on the sticker changes for the trunk latch placed one (purple, blue, red) and also for the valve cover sticker (most likely in the US).
I have always thought the rear axle sticker to be placed on the A pillar between the hinges. But did not consider if it was factory or dealer installed. While judging (I judge for Mercedes Benz Club of America) at Legends of the Autobahn in Monterey, I saw one 111 car with the axle sticker on the differential?!