it isn't the one that goes to the brake booster ? There should be a sticker showing the routing of your vacuum line. LOL you could always go to CARMAX and see if they have a V8 SS , act like your interested and have the sales guy pop the hood.
what I usually use to clean the top end is SEA FOAM. I buy a squirt can and a can i pour into the gas tank. If the squirt can is not available i pour some into a squirt bottle. Squirt some in the TB. Also take off the vacuum line from the brake booster to the intake manifold. i use a differnt hose with a funnel. I pour in the sea foam slowly till the engine dies, then I let it sit for awhile. Don't pour in a lot don't know if hydraulic lock is possible. CAUTION the engine can blow it all back if it back fires through the intake manifold. So its a good idea to wear eye protection. I usuall do this with a gallon or so in the gas tank. Then I go to the gas station , pour in the can of SEA FOAM after reading the directions and then fill up with gas. In the sam vein, I heard an old mechanic when I was a little boy say that he used to sprinkle water into the carburetor of a running car, which he said the water would hit hot carbon deposits and cause them to shatter. So ther'* your choices SEAFOM or WATER.