Rob, the engine number would also have to be stamped in the following locations:
- the right hand side of the engine, at the back, near the bellhousing
- the left hand side of the cylinder head (probably twice)
In addition, if the gearbox is original to the engine, a number quite close to or even exactly the same as the engine number should be stamped on the right hand side of the gearbox. You have to be under the car to be able to see it. An example: engine 100 D 650, gearbox BW CR 12 650.
As far as I know there is no difference in stamping locations between 100 D and 100 D2 engine types. Only the letter D and digits got a bit smaller on later engines.
Would you still like pictures?
Jerry