‘76 Duster with a 360 and sunroof (not mine)

My first mopar was a 76' Duster with a factory 360. Your correct it was an option and no longer a package. I had the build sheet for the car and they used the E58 spec 360 which was pretty much the same as the later Lil Red Express trucks.

Because it was an option and not a model I couldn't find the build numbers. Still wish I had never sold that car.