79 250, what is this fitting?

[Volfandt]

79 250 w/the integrated head and 2bbl manifold. I'm going over this engine capping and/or removing unnecessary pollution and leaky vacuum devices.
I removed this fitting hoping it was in a water jacket but it wasn't. It had a small amount of soot or dried oil in it. The fitting is hollow with a small output port and a slightly larger output port. Whatever is generated in the void in the block will exit out both outputs.