The little plate is unusual as it does not seem to have a definition of Sach Nr or Gerate Nr or Werk Nr.
It is a fairly early plate and the 323/ C part is definitely the engine type it is for and I think the 696 is probably the part number, so it is likely the Sach Nr "323/C 696" . The Ersatzteilliste would prove it, or not. However, as the plate is so simple, it is possible that it combines the engine type "323/C" with a simple Werk Nr "696".
Unfortunately, I do not have more info.
Eng