The Duster was not changed significantly for 1972. New surface-mount side marker lights replaced the previous flush-mount items, the tail lamps became larger, one-piece units.
For 1974, Plymouth replaced the 340 with a 360 cu in (5.9 L) version of the corporate LA-series V8, with lower performance due to U.S. government-imposed emissions regulations. The 1974 "E58" 360 engine produced 245 hp (183 kW).
Following the design changes on the Valiant models, the Duster also received a new hood, grille, front fenders, bumpers, and taillights for 1973. The taillights on previous years mounted from the inside and had a flush appearance.
The Duster was a success for Plymouth, so much so that in 1971 Dodge requested and received a version, the Demon. In response, Plymouth was given a version of the Dodge Dart Swinger 2-door hardtop named the Plymouth Scamp.
The Plymouth Duster introduced in 1970 was all Valiant from the cowl forward, but the rest of the car's sheet metal, save door skins, was completely different. The design incorporated a semi-fastback roof and a special rear valance with twin horizontal taillights, unusual for having no bezels.