Historic Truck Brands

Diamonds – T and Reo

The most significant contributor to this Diamond-brand duo was Diamond T that produced trucks from 1911 until 1967. Reo came later into the truck business and both brands became part of White Trucks in 1957/8.

The Diamond T Motor Car Company was founded in Chicago in 1905 by C A Tilt, whose father was a successful shoe maker, supplying the Marshall Field Company. The vehicle badge was originally on the company’s shoes: a diamond representing quality and durability, enclosing a ’T’, forTilt.

Initial Diamond T production was passenger cars, until a Michigan plumbing business requested a truck version, after a successful experience with Diamond T cars. This chain-drive vehicle was powered by a Continental petrol, four-cylinder engine and used a Brown Lipe transmission and Timken axles in an O A Smith frame. It proved to be very successful, dictating the company’s future progress.

From 1911 truck sales boomed and, before World War One, there were many Diamond T dealers across the United States as in many export markets.

WWI generated plenty of new business and Diamond T produced three- to five-ton ‘Liberty’ trucks for the War effort on a new production line. These Class B trucks were powered by Hinkley four-cylinder engines. 

In the 1920s Diamond Ts acquired rubber-mounted enclosed cabs, electric lights and pneumatic tyre options.

Diamond T managed to postpone the effects of the Great Depression, because in 1928 C A Tilt adopted breakthrough streamlined designs, with raked windscreens and vee-d grilles that caught its competitors napping. Also, power output increased with the adoption of 60hp six-cylinder Hercules engines.

Diamond T’s advertising message changed from ‘The nation’s freight car’ to ‘The handsomest truck in America’. 

In 1933 came the car-like-styled 1.5-ton Model 211, followed by the first Diamond T COE in 1937. The cab didn’t tilt, but the entire powertrain was mounted on a slide-forward sub-frame. 

Another 1937 breakthrough was an all-steel – no wood framing – cab for the 3/4-ton light truck. A year later came the first 100,000-mile warranty.

World War Two dictated designs and production until 1945, but by 1949 there were no fewer than 19 Diamond T models available – probably too many, some critics have said. C A Tilt retired in favour of his brother, Ned, in 1947.

In the 1950s Diamond T offered COE, conventional school bus and specialised chassis in a wide choice of wheelbases; powered by petrol, diesel and LPG engines from Hercules, Cummins, Detroit Diesel and Caterpillar; offering transmissions by Fuller, Borg Warner, Spicer, Clark and New Process.

In 1954, C A Tilt passed away from a sudden heart attack and White Motor Corporation stared making takeover noises. Diamond T resisted, but in 1958 the deed was done. White had already purchased Reo the year before.

White continued to produce trucks under the Diamond T brand, but they became progressively more White. In 1967 White blended Diamond T and Reo trucks under the Diamond Reo brand, which was sold off in 1971.



Ransom E. Olds was an entrepreneur who founded multiple companies in the automobile industry. In 1897 Olds founded the Olds Motor Vehicle Company, makers of Oldsmobile that later became part of General Motors. In 1905 Olds left Oldsmobile and established a new company, Reo Motor Car Company, in Lansing, Michigan. (REO were his initials.)

In 1915 the company moved into making trucks and introduced the legendary 3/4-ton Reo Speed Wagon. It quickly became known as one of the best vehicles in the market.  The Speed Wagon was the first vehicle in the pickup generation. Its success was replicated by other manufacturers, with 60 individual variations soon appearing.

REO’s Speed Wagon continued to evolve, adding electric starters and lighting, shaft-driven axles, and pneumatic tires mounted on steel wheels. 

The company expanded the option list for its lightweight Speed Wagons and added heavier versions with up to two tons capacity. 

More than 125,000 Speed Wagons were produced by 1925.

In 1925 the Model G Heavy Duty Speed Wagon was launched with a six-cylinder 50hp Reo T-6 petrol engine. The truck had a two-ton capacity and featured a double frame for strength and an oversize radiator for improved cooling. 

A three-ton Model GA was introduced in 1929, with a dual-wheel rear axle. The truck was powered by a six-cylinder, gasoline Reo Gold Crown engine that was a truck engine, not a passenger car engine. 

Later, a four-ton, 101hp model was introduced, with a lazy-axle tandem rear option. 

When the US Stock Market crashed in 1929, the company suffered and in 1936, Reo abandoned car manufacturing to concentrate on trucks. 

Orders for trucks for the World War Two effort improved cash flow, but Reo didn’t flourish in the post-War era.

In 1954 Reo was sold to the Bohn Aluminum & Brass Corporation of Detroit, and three years later became a subsidiary of the White Motor Company. White merged Reo with Diamond T trucks in 1967 to form Diamond Reo Trucks, Inc.


Diamond Reo

In 1971 White sold off Diamond Reo that became Diamond Reo Trucks Inc. The new company produced Royale COE and Apollo conventional models, followed by the Rogue and Raider, powered by Caterpillar, Cummins or Detroit Diesel engines. However, the company’s life was short-lived and receivers were appointed in 1975.

Diamond Reo changed hands twice, before the bonneted Giant was released by new owner, Osterlund Inc. The Giant 6×4 used the steel Autocar cab and engines from Cummins or Detroit Diesel.

The 1985 product release was the T-line, with two bonnet lengths, based on frames and cabs from Navistar. Production ceased in 2010.

The 2018 reintroduction of the Diamond Reo nameplate in Australia came courtesy of Daysworth, best known for its yard tractors and a previous Diamond Reo association with Giant models that it imported Down Under.

The new Diamond Reo is a COE, made in China by CNHTC, using what looks like the previous-generation Volvo cab, MAN-technology engines, rated at 350-540hp and ZF manual or AMT gearboxes.

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