The vac port on the metering block is a "ported vacuum" source. It is where the Mopar brand vacuum advance distributors are supposed to be hooked to.

Ryan "Bigs" '73 Duster (BLKDUST) - Black, 100% factory sheet metal, flat hood, 346 cid, J Heads, and a bench seat. http://s268.photobucket.com/albums/jj1/bigsbigelow/ Best to date: 12.40 @ 109 mph