In Mopar nomenclature, Plymouth was always an economy or muscle car brand. In fact, they were dedicated to family cars, small sedans or two-door coupes. During their history, they did produce some pickup trucks, but never any off-road models. Dodge was more into that market with a series of SUV models and big success in that field.
However, in the late ’70s, Plymouth decided to try its luck in the off-road market with the Trailduster. It was a two-door, all-wheel-drive vehicle identical to the Dodge Ramcharger. The idea worked since the Trailduster was a good looking truck, similar to the Ramcharger, but with different trim and details. To promote the product in that market, Plymouth even offered all-wheel drive at a lower price with more equipment than Dodge.
But, they had no luck, so after a couple of years, they discontinued the Trailduster although the Ramcharger stayed on the market. All this means the Trailduster is rare and could be expensive in the near future. And sadly, it also means you will have to search all over the country for a decent example.