Help- '79 SC Vacuum line- photos

[GIBSON]

Just helped a friend R/R his new 1979 SC engine/trans. We resealed, cleaned etc. We found one vacuum line we could not identify and assumed (like fools) that we would find where it goes
when the engine was in place. Wrong. It's obviously a functioning line, I've included some photos. Anybody have any idea where it goes? The car runs ok, stumbles a bit at idle but once off idle seems to run fine. Thanks.

[azasadny]

Is that the vacuum advance for the distributor? Looks like the same diameter (small) on my '74.

[GIBSON]

Art, I was looking around the area the hose would match up to
in terms of length and found this port behind the cruise control vent port. I'm assuming there is vacuum to the cruise unit, this might be it. It's a perfect fit.....

[biosurfer1]

bruce...

how hard would the lines be to hook up after the engine was already in the car. i have ( i think) a vacuum leak and was planning on replacing them, but wasnt sure if it was a job that needed the engine to be out of the car...any thoughts?

also, if you can remember the line lengths and diameters, it would be a big help...

thanks!

[GIBSON]

Some of the lines would be easy, others you'd really have to struggle with. You'd want to remove the fan (the electric one), the A/C unit if you have one, and you would still have a difficult time with some of the lines. Some of the lines are fabric type, others rubber so you'd want to have both lines available.
I think to do a really good job you'd want to drop the engine, maybe a partial drop would help- you'd get some improved access but it would still be a struggle.
I don't know all the lengths but I could measure specific ones if you want. It's not my car but I can get to it easily.

[targa80]

The cruise control does use a vacuum line and also has a breather line.