wrong ac compressor

[qualicas]

I'm new to BMW and I'm trying to get up to speed. I have a 1995 318IS. I'm pulling the engine to fix a spun bearing. I happened to notice that the AC compressor mounts differently than the one shown in Bentley. I just did a search and found it is from a E30 series! What happened? It looks like it is supposed to be there. The engine looks original, all lines etc look original.
Did someone modify this? Do I just use this compressor or should I update to the correct one?