W123 Auto to Manual conversion

[Keystoner16]

I'm looking at a 1982 240D. At first I was thinking of this car as a possible parts car, but now I am considering actually having it be the project car.
The body is in better condition overall, and it does not have a sunroof (a huge plus given my recent experiences with sunroofs in these cars).
The car is an auto, and the trans has some sort of shifting issue. Maybe vacuum related, maybe something else.


I already have a 1981 240D with a manual transmission.(The current project car).
I am wondering what all is entailed in converting an auto car to a manual?
Is there any differences with the electrical harness that will need to be addressed?


Any information is greatly appreciated. Thanks.