There is a vacuum line that comes, I think, out of the passenger side firewall and runs behind the distributor toward the drivers side. It seems to disappear behind the mass of connectors for computer stuff. I left it unhooked after my recent LT1 intake swap and just remembered it. Also it's a plastic type line.

 

That 1/8" line is a vacuum source for the cruise control & AC mode control. It tees off inside the harness & goes to the cruise servo inthe left front & the other goes to the vacuum selector on the AC/heater control.

 

ok, on mine it also had a T where it connected to the cruise control "thingy" and went inside my fender right by the battery. What does it go to from there?