Not so sure how helpful the dial part numbers are as VDO may have made several different dials, even for cars having the same rear end ratio (Autobox vs Stick, 4-speed vs 5-speed, 80 mph vs 85, black center buttons vs bright aluminum)
If it hasn't worn of fallen off, there is what appears to be a calibration number on the rear paper stickers of these speedometers.
My P-N-P Euro non-turbo 300D speedometer sticker is marked k=1360, while my spare 240D speedometer is marked k=1320, and another spare I have (origin unknown but MIGHT be from a turbo-diesel) is stickered k=1425.

Happy Motoring, Mark

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DrDKW