There may have been differences in Australia and maybe with later 113s but I can tell you about my 1966 230SL, USA version. It was built at the end of 1965 and I bought it new in February, 1966. It is registered as a 1966. In those times, as the year came to a close, the USA dealers sent the vin of the cars in stock and Mercedes sent them new paperwork so that the could be registered as the next year's model. Cannot be done now but it could be done then.
As far as owner's manual, I have the owner's manual as delivered for my car. There is no year on it. It just says "230SL Owner's Manual". Everything is in 5 languages, German, English, Swedish, Danish and Dutch or at least that is what I think the last 3 languages are.
The translations to English are sometimes interesting but, for the most part, the manual is pretty good. My favorite sentence in the owner's manual is in the coolants section which says "Use clean water with a low calcium content or well filtered river water.". I lived South Australia for a time with our water supplied from the Murray River. I am not sure you could ever filter Murray River water enough to be used in a car!