Mysterious vacuum connection off manifold

[Vgrizzw]

I'm just trying to identify the vacuum line coming off the rear of the manifold. I can't find it shown on any diagrams and the end isn't hooked up so I just want to put it back where it goes.
Thanks

84' I-6 manual trans

It's coming off a 90 degree fitting in the rear most intake manifold runner. I tried to upload my pic buts its too large at the moment.

[amcfool1]

hi, it is probably the feed for your axle/diff  disconnect switch/motors , good luck, gz

[Vgrizzw]

I figured it might be. The only other loose end was on the passenger side of the valve cover and it led to the underside of the car. That's where I finally chose to hook it up to but couldn't find any info to validate, but I'll stick with it for now. Thanks for your response.

[macdude443]

On my '86 I have a 90* fitting with two ports at the back of the intake.  One is for cruise control and the other runs to the HVAC control in the dash to switch the coolant valve on and off for the AC.