HVAC Vacuum Line

[joshmikow]

I recently had the engine in my 1987 K5 blazer rebuilt and as a process of pulling the engine out we disconnected the vacuum line for the HVAC redirector.

I've done research everywhere I can and I haven't been able to figure out where to plug it into. Now I don't have a defroster and with it getting colder it is noticeable.

Can anyone tell me where to plug the vacuum line that comes out of the firewall in? A picture would be great as well if it is not clear where it goes.