M-135 Series 2 1/2-ton, 6x6 Trucks

The M-135 Series of 2 1/2 ton cargo trucks was the first successor to the World War II "deuce and a half" that was the backbone of mobility throughout all theaters of that war. It was a hard act to follow, but technology had improved and General Motors was able to create a whole new generation of worthy vehicles.

M221 Truck, Tractor, 2 1/2 ton, 6x6 at the Fort Snelling (MN) Military Museum
M221 Truck, Tractor, 2 1/2 ton, 6x6 at the Fort Snelling (MN) Military Museum.

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US Military M135-Series 2 1/2-ton, 6x6 Trucks (G-749)

Sixty-inch anti-aircraft searchlight mounted on M-211 chassis adapted to provide a flat platform for the light, its generator and operator. Engineer Research and Development Laboratories, Ft. Belvoir, VA, 1950s
Sixty-inch anti-aircraft searchlight mounted on M-211 chassis adapted to provide a flat platform for the light, its generator and operator. Engineer Research and Development Laboratories, Ft. Belvoir, VA, 1950s.

Following its success with the WW II CCKW, in 1951 General Motors developed and began producing the M-135 (standard nomenclature G-749) family of trucks. The design of this series included many new features that were quite innovative for the time:

  • Automatic transmission (GM Hydra-matic)
  • Air assisted power brakes
  • Single large tires (only the M135)
  • M-series standardized improvements:
    • 24v electrical system
    • Sealed, waterproof ignition

All trucks of the series were equipped with 6x6 drive, powered by the GMC 302 6 cal in-line, valve-in-head 130 hp gasoline engine. The M135 was equipped with 11:00x20 tires with singles on the rear while all other models had 9:00x20 tires with doubles on each rear axle. The transmission had four forward speeds in two speed ranges. All the driver had to do was select the speed range. The transfer case was single speed, but a lever allowed it to be put into neutral. The axles were full floating hypoid single-reduction type with banjo housings. Front and both rear differentials were interchangeable.

All of the M-135 series trucks were soft-top, except the M220 shop van. The cargo, dump, and tractor models could be equipped with a 10,000 lb. winch without changing the overall length. The windshields had two sections which could be separately opened for ventilation. The front bumper had distinctive holes to reduce its weight.

The M135-series trucks were produced by GMC from 1950 through 1955 and were superseded in the U.S. military by the M35-series vehicles. The M135, M211 and other vehicles of this series -- affectionately known as the "round-nose jimmy" -- remained in service in the National Guard and Reserve components as well as in the military of U.S. allies for decades.

Truck models in the M-135 Series include:

The M135 and M211 cargo trucks mainly differ in that the M211 has dual rear wheels (with smaller tires) and a flat cargo body whereas the M135 has single wheels on each axle and wheel wells in the cargo box.

Photos and additional information about each of the M-135 series trucks are on the pages linked from the list above.

Manuals for the M-135 series of trucks include:

  • TM 9-819A Operation and Organizational Maintenance (July 1951)
  • TM 9-8024 Operation and Organizational Maintenance (October 1955)
  • TM 9-8025-1 Engine
  • TM 9-8025-2 Transmission
  • TM 9-1819AA Engine Rebuild
  • TM 9-1819AB Transmission Rebuild
  • TM 9-1819AC Power Train

Recommended Books with more about M135-series Trucks