x2, x3, x4, etc. (to Steve St. Laurent's post)
Cummins has ZERO responsibility for these engines or anything else that they've sold to Dodge/Chrysler. Don't be fooled by individual experiences or other claims... a poster on the wall is not a contract.
As others have said here, that does NOT mean that a dealer can't authorize ANY other shop to perform work for THEM... and it makes sense that they might send a repair to a Cummins shop.
DC isn't going to pay for anything they don't have to. If you go to a non-Chrysler shop to get something fixed you will not get reimbursed unless a dealer decides to pull a paper-work stunt to fool Chrysler for you... and you can bet that Chrysler is as hard on the dealers as anyone, especially if they get caught "cheating". From the corporate perspective, dealerships are barely above the end users/owners when it comes to warranty claims.
Having said all that, there are probably quite a few Cummins shops around the country who already have a relationship established with one or more Chrysler dealerships where they can call up and pre-authorize work to be performed under warranty. In those cases it might seem like Cummins is paying the bill but I guarantee it'll either be Chrysler, you, or the dealership if Chrysler later denies it. Chrysler will pinch a dealer just as fast as a customer... and a dealership has a lot more to lose than the car/truck owner. Most, if not all US "auto" warranties border on organized crime, IMHO. If they were regulated as "insurance" under various state laws, most would be considered fraudulent. Never assume that they are "happy" to absorb warranty costs... someone gets paid to count all those beans too.
Edit: waited too long to save this post... expected it to follow Steve's.