The -A1 upgrade had a Mack ENDT-673, a 673 cu in (11.0 L) turbocharged inline 6 cylinder diesel engine developing 210 hp (160 kW) at 2100 rpm.

The basic cargo version was designed to transport a 5-ton (4,500 kg), 14 ft (4.3 m) long load over all terrain in all weather.

Rushed into production by International Harvester in 1951, soon Kaiser (renamed Kaiser-Jeep in 1963) also became a major manufacturer, with Diamond T and Mack building smaller numbers.

The -A1 upgrade had a Mack ENDT-673, a 673 cu in (11.0 L) turbocharged inline 6 cylinder diesel engine developing 210 hp (160 kW) at 2100 rpm.

The -A2 upgrade had a Continental LDS-465-1A, a 478 cu in (7.8 L) turbocharged inline 6 cylinder multifuel engine developing 175 hp (130 kW) at 2100 rpm.

[3][4][5] Gas engine models have a down-swept exhaust exiting from under the body just ahead of the righthand front set of rear wheels.

Of important note, A2's with a factory build date prior 1964 originally were gas engine models.

However, some converts retained their original gas model direct-5th transmission which gave closer gear ratios but a top speed of only 45 mph with a multifuel due to the lower top rpm allowed on that engine compared to a gas engine.

There was also an M139 heavy duty extra long chassis for extreme service, including the Honest John rocket launcher truck.

It had hinged doors with roll-up windows, a folding windshield, and a removable canvas roof.

Cargo trucks and tractors could be fitted with a ring mount for a M2 Browning machine gun.

Side racks, troop seats, and overhead bows with a canvas cover were standard.

[7][12] The M51 was a dump truck used to haul sand, gravel, dirt, rubble, scrap, and other bulk materials.

They could be equipped with overhead bows, tarpaulin, and troop seats, but the relatively small size of the body limited their passenger or cargo load.

[4][22] In addition to standardized models, bare chassis cabs were produced for specialty bodies.

None had diesel or multi-fuel engines for weight reasons, and they had stronger axles with a lower final drive ratio.