Heater/ac box vacuum supply

[fireguyfire]

I'm reassembling my 68 which is an a/c car. I have all of the vacuum hoses reconnected from the fan switches to the vacuum pods on the heater box. The only hose left has a grommet on it and in the shop manual is simply labelled "vacuum supply". My problems are, I don't know where this hose is supposed to go through the firewall, and where it terminates to supply the vacuum to the system ( I didn't take the car apart) . Any help/ photos would be greatly appreciated!

[C928BRAN]

Comes through a grommet in firewall, close to the a/c lines, and connects to a vacuum tree, with the power brakes, in the back of the intake.

[Just 6T9 CHGR]

Circled in green

[fireguyfire]

awesome, thanks guys!