unknown truck manifold port

[grad70]

I have started a L96/4l80e swap into my '70 c10. I am having issues determining what the port is for on the passenger side of the truck intake manifold. I'm on a work trip so I can't take anymore pics than what I have below. I'm hoping to find out where it should go/connect to before o get back in case I need to order more parts.

I have used this site a lot to get to where I'm currently at and wanted to thank you ahead of time. I have been unable to find this info for the last week of searching.