That chain looks to have had contact with some part from a failed vac pump. The small cylindrical pin looks like it held on one of the parts in the vac pump. Balls look right size too.

Clean up really well, I'd want to pull the motor so I could clean everything really well. I'd really want to check the bearings for fragments.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.