This old car makes be feel ignorant. Basic Questions inside.

I learned the hard way about vented gas cap. As a young man I bought a CST-10 68 327 short bed Chevy and one of the first things I bought for it was a chrome gas cap. This is when they use to have the gas tank behind the front seat! I would drive it and then it would die? I thought the gas gauge was broke so I added some gas. Then it would happen again, and again. Till and old mechanic told me I might have a non vented gas cap. It would run until the fuel pump couldn't pull gas out of the tank, then every time I took the cap off I was re-leaving the vacuum created in the tank. If your car is running with the vent line plugged you must have a vented cap on your Duster.