Not long ago, Chrysler's bankruptcy allowed the automaker to cancel contracts that were no longer desirable for the automaker moving forward. The deal with Cummins for the light duty diesel was one such contract, though later reports indicated that the deal could potentially be revived. According to an unnamed source quoted by Automotive News (sub. req'd), though, that pairing may be in jeopardy.
In place of the Cummins diesel engine may very well be an oil-burning powerplant from Fiat, the Italian automaker that recently partnered up with the Chrysler. In related news, Chrysler may possibly withdraw from its joint venture with Hyundai and Mitsubishi to produce the World Engine that's currently used in a number of Chrysler, Dodge and Jeep vehicles. As you may have guessed, the replacement powerplants would almost surely be sourced from Fiat.
[Source: Automotive News - Sub. Req'd]