I have seen two Cummins Diesel conversions in 1-ton AD trucks. I would expect the conversion on the bigger truck to be similar.
One of the two I've seen was tooling down the freeway and I passed it on the way to a truck show. I later saw it setting in the parking lot at the show. I looked it over but didn't get to talk to the owner.
The other was built by a guy in Texas who documented the swap on the forum at OldGMCTrucks.com. That guy I know used a Dodge pickup as a donor for many of the parts. He modified the firewall to get the six cylinder motor to fit.
