Check this out, I've never seen one of these before on a normally aspirated car - Vacuum gauge. The Smith's gauge guy who does repair said these are fairly uncommon / rare. There is a hose connected to the back of the gauge that runs all the way to the intake manifold in the engine. The hose was clamped off with some small clamp - I'm not sure why. I assumed it was because the gauge was broken, or the hose had a break and was leaking. So, I decided to test it...
Here's the cool gauge:
Here's where it connects to intake manifold:
Here's how you test it - suck on it, look at the gauge, stick your tongue on the end and hold it for a minute or so to see if the gauge goes down (signalling a leak in the system). No leaks! I'm not sure why this was clamped off (maybe I will discover the reason in the future).
-Wayne