This is an excellent question I'd also be curious about. The main reason to know is so that you can correctly source spare engine parts with some confidence. Not all parts are easy to figure out. I *think* I currently have a factory rebuilt engine from a 280SE, installed sometime in the early 90's, but I'm not completely sure which type of oil pan, pump, and pickup are correct for this specific block. I shared part numbers with a well known parts supplier and they didn't think my oil pump was from an SL or an SE. It works fine but I'm stumped.
Reverse lookup of the engine serial number would be a great help.