i can't imagine my mighty Dodge/Cummins with a hydrogen tank, but apparently Cummins can...
Cummins declared that the B engine, used by Ram for three decades (currently 6.7 liters in Rams), will be made in forms that can burn diesel, natural gas, or hydrogen—not to mention gasoline and propane. (The engine is already made in natural gas or diesel versions.)
I'm aware of the technology available to make diesel engines run on natural gas, the trucks used locally by Waste Management have used them for many years...I just can't imagine my Cummins 6.7 liter B engine running on propane or pump gas though...

Diesel costs so much lately that I've even cut back on traveling to out of town gun shows, but I'll stay with it to the end......Ben