Has a newer Hercules engine.
https://offerup.com/item/detail/780977725/
“It’s a 1958 military mule it originally had a four-cylinder Willys engine that we still have but now it has a two cylinder Hercules engine which has more power and that motor came in the later models we bought the engine brand new and put it in it has brand new tires on the front 4 Wheel drive and four wheel steering I made 11,000 of them and 6000 of them were left in Vietnam”