For what it's worth Allpar is saying there is evidence that FCA is working on a straight 6 diesel engines that could make its way to the JL/JT Wrangler, though that last bit seems more speculation than anything. I wish this whole diesel scandal could be behind us and we'd have some clear answers if it is coming or not.
New straight-six diesels, too?
Alongside new gasoline straight-six engines from FCA Corporate, we have seen some evidence that Fiat Powertrain is working on straight-six diesel engines, possibly based on a new generation of the FPT four-cylinders used in the Ram ProMaster and Fiat Ducato vans.
What would the diesel be good for? We can think of a few uses within the American brands, quite aside from Fiat commercial applications.
For one, it could replace the expensive VM 3-liter V6 diesel used in Ram 1500 pickups, reducing the pressure on VM to produce ever-increasing numbers of those engines. That would allow more of the engines to be used in more Maseratis, Alfa Romeos, Grand Cherokees, and such. It could even be a base diesel for the Ram 2500, at much lower cost than the top-range Cummins.
Another use could be in the Jeep Wrangler and the upcoming Wrangler-based pickup; standardizing on inline engines could help engineers to dramatically improve the off-road abilities of both, by providing more room for suspension movement.
That alone would be justification enough, but chances are there are numerous places for such an engine in the Fiat Chrysler empire.