There's a tag on the front of the block on my 81 300SD. The tag reads:

Original Mercedes Benz
Tauschaggregat
Teil Nr 617 010 8902 82
Bm 617951 Agg Nr 876024

The PO told me that the engine was replaced at 150K miles (now at 294K miles). No documentation.

Does this tag suggest that this is a factory supplied replacement or a dealer rebuild?

Thanks,
Sixto
91 300SE
87 300SDL
81 300SD