Phil,
Had to be a 912E which had the T4. The 912 used the old 356 1600 T1-style engine. I don't know what type of emission equipment the 912 may have had in its final years.
By the way, I'm surprised the 912E drove the AC compressor with that tripod drive. Stronger than I thought!
Bob,
What does that second fan pulley do to the compressor speed? That baby must be screaming!
Mike