Chances are it is a MEP-016c gasoline generator that was converted to a MEP-016d by replacing the gasoline engine with a 1 cylinder Diesel, often times the data plates were not changed. I just bought a couple of them last month from GL with the listing the other way around, listed as gasoline, but obviously diesel yanmar in the photo. An easy way to tell is the Yanmar's have a modern recoil pull starter, the old gasoline units had a manual wrap around pull rope pulley on the end.
Ike
p.s. if it is a MEP-016D yanmar repower, they are great little units, but I am not sure I would drive 4.5 hours for one, you might look into logistics shipping services as the repowers only weigh about 280 pounds.