I was wondering if anybody has looked some of the small-diesel
manufacturers?

I know that Kubota makes a couple of diesels in the 50-100 hp range,
one is even turbocharged. I expect the same is true with Yanmar. I
looked up the Italian manufacturer of the new Jeep Liberty diesel a
while back, they had a few engines in the right power range too.
(Though I have no idea about the weights)

-Matt