I took my cruise control assembly that is under the hood out of my 1985 F-150 to clean it up and repaint it. I noticed what looks like an empty vacuum port on the top and toward the back of the plastic part of the assembly. This might be a silly question, but does the cruise control system require engine vacuum to operate? If so, where does the vacuum line typically hook up?

I have a two-prong vacuum source on the metal side of the cruise control assembly that has a short "C" shaped molded vacuum hose attached to one port that goes over the top of the cruise assembly and attaches to a port on the plastic part of the assembly. And then another long hose is attached from the other prong (next to the molded "C" hose) that goes to the firewall of the truck and inside the truck under the dashboard. That's it. What's left is an open port(?) toward the back end and on top of the plastic part of the cruise control assembly. Does a vacuum line of some sort go here?

 

Yes it uses uses vacumm. I think mine comes of the manifold.