I have a 2003 slk32 amg. The right rear running light has never had a bulb in it because the knock out where bulb would go is Still intact , never removed from factory . Is this right.

 

Not sure about the slk32 amg's but my slk230 K S rear right light is the same way, I even popped in a bulb in it but still no light, the wiring to the right light has one or two wires less than the left one, if I remember correctly, so it must be factory standard

Edit: Accidentally found the answer, rear fog lights are driver side only