Corvette Performance - question in ls6 driver valve cover rear plug

what is that thing called on the back of the driver side valve cover, or what is the part number.

im doing an lq4 swap with an ls6 valley cover and need to plug the back of the driver side valve cover. i want it to look nice and i think i have seen vettes come with a metal piece with a vacuum cap.

does that make sense? lol

you can barely see it on this pic

http://www.gmhorsepower.com/images/LS6-5-7-Liter-Base.jpg

Do you see it here:

http://www.trademotion.com/schematics/mechanical/NTP030.gif