hmmwv and cummins 5.9

[Skrilex]

I guess the silver lining is that if they had used a 6bt in the humvee there’s no way that I could afford one lol. That crummy old 6.2 is the thing that lowers them to within my reach.

 

[dilvoy]

That and I am convinced that somebody at the DOD has a brother in law at GM. There is no other way that they used some of this junk so long.

The military was buying new dodges with flat head sixes into the late sixties. If the vehicle did it's job, they kept buying it with none or minimal changes with maybe some bigger changes if something new came up. Same with the Humvee.
To put the Cummins engine would require a very large redesign of the vehicle.