That's a balancer for a bunch of different late model BMW's with a specific options package. OE BMW number is 11 23 7 561 312 . Dayco is the OEM and the aftermarket part number is PB1745N. That balancer is worth 3-500 bucks. Lucky you.
I been working on cars since I was 5yo and I'm the primary mechanic at me and my dad's shop. We work on literally everything. Just looking at that part tells me that it's from a later 6 cyl BMW and I noticed it has 2 belt drives on it and the only ones that have that are the ones with 4 zone climate iirc. I think maybe I been in the business too long. HahaYour the man ! How did you figure it out ?