Chevy 250 with funky valve cover

This is in a 68 C10 I'm taking a look at - appears to be a 250 six but what's the story on the weird valve cover?

 

something to do with emissions, a low buck AIR system?

See if the intake manifold is integral with the head (one piece). It's the later design of the engine, which most guys don't like. I don't remember what year they started using them, but I think it was mid 70s.

 

@squirrel never sleeps! That would be my guess as well.

 

squirrel nailed it! Is there anything he doesn’t know?

 

Squirrel is correct. Emissions engine made towards the end of production, before they replaced the inlines with the V6.
Major change besides the strange valve cover is the integral manifold a la the small falcon inline six of a couple decades earlier.