text: Cummins Turbo Diesel After 1978, the Chrysler RB engine was discontinued and therefore no longer offered in Dodge pickup trucks. Without a "big-block" gasoline engine or diesel, Dodge's heavier-duty models had a severe power disadvantage over the competition, and thus began losing potential customers in the commercial market. Rather than developing a brand-new engine, Chrysler signed a deal with commercial engine manufacturer Cummins to use a version of its 5.9L B Series engine in the Ram trucks. This proved to be a mutually beneficial deal, allowing Cummins to expand its product output and Dodge to have a competitive engine for its heavy-duty models. The introduction of the Cummins Turbo Diesel model in 1989 coincided with the first sales increase for Ram trucks in several years. The Cummins was coupled with a heavier-duty version of the A727 automatic or a 5-speed manual transmission and was available on 250 and 350 pickups and pickup-based chassis-cab trucks above 8,500 pounds GVWR. This diesel engine option was different from the diesel engines offered in Ford and GM trucks in that the Cummins features direct injection, whereas the Ford and GM diesels feature indirect injection. This also means that the Cummins does not have to rely on glow plugs. The Cummins is a straight-six engine, whereas the GM and Ford diesel engines are V8 engines. Additionally, the Cummins is turbocharged, while the 6.2L GM/DDC and 7.3L IDI Ford/IH are naturally aspirated.
  This was not actually the first engine to debut in Dodge pickup trucks as a diesel option. The 1978 D-series models were available with a Mitsubishi naturally-aspirated diesel, but it was seldom ordered. The Cummins diesel was in short supply the first two years, but for 1991, Dodge managed to ramp up production.
  Partway through the 1991 model year, Dodge started using 350 (one-ton) frames in Ram 250 Cummins and Club Cab models.
  Engines
  Special editions
  Prospector – Prospector was a package available throughout the 1980s that usually included a different fuel tank, cloth seat, and carpeting. In the late 1980s, a light package, as well as the large 6×9 mirrors, were added to the list of options. This trim package was carried on until the end of production in 1993.