Try this link and see if it helps any. Shows the grommet going through the fire wall just to the left of the AC unit on the fire wall. Look under the 68-69 PDF, should be the top one.
http://www.gobookee.net/69-chevelle-...-line-diagram/
I'm not an expert on 69, but I thought there no vacuum pods on the 69's were 70 did have them?
This picture may not be for a 69