Nice collection you have there!
The engine number directs us to the VIN the engine was in originally (and perhaps still is), an 82 Euro RHD 323i auto built june 82.
To find the original VIN there are several options, apart from the ID tag in the left side of the boot (not on all cars), on the crossbeam underneath the dash (can only be seen with the dash removed), and perhaps if the production label is still fitted to the bottom of the rear seat.
I guess that the OTHER






