Where does the vacuum line plug into the carburetor at that's coming out of the bottom of my distributor cap and also is that the only vacuum line that must be hooked up to make my truck run and it's a 1984 Nissan pickup
That vacuum line is for the vacuum advance of the ignition system and is not necessary for the engine to run. It helps it to run better, but is not required. If you have a no start condition, you need to first determine what you are missing for an engine to have continued combustion. Fuel, Spark, and Compression are the three things an engine require to run. These also have to happen in the correct time. If you have verified that you have spark, and you have fuel, and you have compression, you then have to verify that the engine is in time.
Answers & Comments
That vacuum line is for the vacuum advance of the ignition system and is not necessary for the engine to run. It helps it to run better, but is not required. If you have a no start condition, you need to first determine what you are missing for an engine to have continued combustion. Fuel, Spark, and Compression are the three things an engine require to run. These also have to happen in the correct time. If you have verified that you have spark, and you have fuel, and you have compression, you then have to verify that the engine is in time.