Nope, I was surprised to learn a while back that both are correct. When Chevy introduced them in 1973, they ran an ad campaign where they called it the "Big Do

Nope, I was surprised to learn a while back that both are correct. When Chevy introduced them in 1973, they ran an ad campaign where they called it the "Big Dooley": https://www.vintagepaperads.com/assets/images/CQ0501.jpg https://www.vintagepaperads.com/assets/images/CQ0501.jpg I've always called is a "dually", but the ad is older than I am, so...