For those who puzzle about manual/automatic production numbers, for what it is worth, in case it is known or immaterial - ignore it.
Looking at breather parts, I came across production changes (different parts used) for the following engine numbers, for 127981, so 230SL:
Up to engine 981 10/50,20/60 010786 981 12/52,22/62 002990
As of - up to 981 10/50,20/60 010787 - 014471 981 12/52,22/62 002991 - 005668
This is 20139 engines. 19832 230SL were produced. Looks like 1/3rd were automatic, give or take. This is assuming the change happened given day.