Recently replaced spark plugs which were a pain in the butt, drove to work the next morning and realized only the defrosted works. I check out the vacuum lines and notice the vacuum canister ball thing is missing a line, it must’ve come off when I was doing plugs. With research the one on the ball is the main vacuum source, the one that’s missing is supposed to go in the firewall and it’s gray? But I. Don’t see a gray line that is disconnected. A gray line that comes from the firewall splices in to a black line and goes to the heater valve. I can’t seem to find the missing line anywhere

 

Then it must've fallen off while driving.
IIRC, you can look under the glovebox and see where it enters the cab through the firewall.
I believe you'd be best off buying a 3' length of the hard plastic line used from a HVAC guy.
I do now know what kind of grommet or bushing is used at the reservoir (ball).