Intake Plug

[jhdeval]

As some may know I recently disassembled my intake/exhaust and replaced the gaskets and machine the exhaust etc. I noticed during all of this a plug in the intake on the 6th cylinder. What is that for? Is there a sensor that is supposed to be there or is it an optional sensor?

 

[powerwagonpaul]

it is a vacum port. for power barkes and such. i have vacum guage hooked there on mine. you can just put a plug in it if you dont need it.

 

[jhdeval]

With that in mind is there a recommened gauge to stick in there for underhood use? I thought that is what it was so I did some pre-research and love the information it can provide.