Another thing that might be of interest to you . . . back in May, Cummins introduced a 2.8 liter diesel for use by Nissan.
As I understand it, it is basically 1/2 of the 5.6 liter V8 diesel block which Cummins developed for Dodge several years ago to use in half-ton pickups. It was "shelved" due to the economy and high fuel prices even though Cummins had already built an entire production line to make the engines.
My old college roommate works as an engineer at Cummins and told me recently (while we were driving around looking at some of Cummins' many test mules) that he was just put on the 5.6 project so it is apparently being revived.