Re: Which engine....?
I love the Dt360. I don't know much about the 366 gas, except that the mechanics at the bus garage said that their fleet mileage doubled when they started using diesel engines. I would bet you will get better performance, hill climbing, and top end speed with the gasser. I think the diesel will be much more reliable, and much better on fuel economy.
My bus' gross vehicle weight was rated for 28,800 pounds. I towed a trailer, people, and stuff on a 5K mile road trip from michigan to nevada and back. This includes crossing the rocky mountains....twice. I put the bus and trailer on a scale and she was over 34,000 pounds. The bus was barely able to do 57 mph on flat ground. I figure that little dt360 ran full throttle for approximately 110 hours roundtrip, and she never missed a beat!
The dt360 doesn't have the power or economy of the cummins 5.9 (although they are the same displacement) but it's got a reputation as a very reliable motor. You can easily turn up the hp and the rpm's a bit without any loss of mpg depending on driving style.
My dt360 had about 170K when i bought it if memory serves me correctly, and over 200K when i sold it. She didn't use hardly a drop of oil, started every time, even in the cold michigan winters.
Quis custodiet ipsos custodes (who will watch the watchmen?)