Chevrolet/GMC B-Series

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Chevrolet B-Series
GMC B-Series
Manufacturer General Motors
Production 1966-2003
Assembly Flint, Michigan
Toluca, Mexico
Body and chassis
Class Type C (conventional)
Layout 4x2
Body style(s)

Cowled chassis

Related GMC TopKick (1992-2003)
Engine(s) gasoline

The Chevrolet and GMC B-Series was a Class 7 medium duty cowled chassis produced by General Motors for the school bus industry. The B-Series was introduced for the 1966 model year. Production of the B-Series ended in 2003; after 1992, it was exclusively bodied by the Blue Bird Corporation until 2003 when it was replaced by the Blue Bird Vision.

Design history[edit]

Prior to the mid-1960s, the medium-duty trucks of General Motors were derived heavily from their full-size pickup truck lines. While based on a stronger chassis, much of the bodywork was shared; aside from engines, the Chevrolet and GMC medium-duty trucks were largely identical to one another. Consequently, the conventional-type school bus chassis used for both divisions were largely the same.


For 1966, the design commonality among the two divisions was split as GMC introduced its own conventional bus chassis. Moving from the medium-duty C/K chassis to the all-new H/J chassis. A forerunner of the GMC Brigadier/Chevrolet Bruin, it featured an entire front fascia fabricated of steel with "butterfly" (side-opening) panels for engine access.[1] Powertrain offerings included gasoline V-8s, diesel V-6 (Detroit Diesel), and gasoline inline-6 engines.

In 1969, a new generation of the C/K medium-duty truck line was introduced. Although Chevrolet would adopt it for bus use, GMC retained its use of the heavier H/J chassis into 1970.


For 1971, GMC would consolidate its bus chassis with the C/K-based one introduced by Chevrolet in 1969. Externally, this change meant a lower profile front hood; instead of the side-access panels, the hood was now hinged from the rear. For 1971, bus chassis were now available with a 3-speed Allison automatic transmission; it was equipped with either a single or two-speed rear axle.

As General Motors redesigned the C/K medium-duty truck line for 1973, the C/K bus chassis would remain based on the 1969 design for another 11 years. Although the chassis itself would not change, the powertrain offerings were consolidated. By 1974, all gasoline engines were built by Chevrolet and all diesel engines were dropped. The engine line primarily consisted of the Chevrolet 292 six, 350 V8, 366 V8, and 427 V8. In 1980, diesel power made its return in an all-new Detroit Diesel 8.2L V8. Dubbed the "Fuel Pincher", it was the first four-stroke engine produced by the company; the engine was available in naturally-aspirated and turbocharged forms. However, as both Ford and International Harvester had both redesigned their medium-duty trucks by the end of 1980, General Motors was largely left behind. In 1984, the Chevrolet/GMC bus chassis saw its first major change in 15 years. Adapting the chassis of the C/K medium-duty introduced in 1973, a tilt-forward cowl was made standard. Along with the "Fuel Pincher" diesel, the powertrain consisted only of two big-block V8s, a 366 and a 427.

From 1984 to 1992, little change would come to the GM conventional bus chassis. In 1985, a modified version went into production for Ward Body Works, which allowed a full-size school bus to be built with the shortened front end typically seen on vehicles based on the much smaller GMC P-chassis. In 1990, the "Fuel Pincher" was discontinued by Detroit Diesel.


In 1992, the GMT 530 chassis was adapted to become the next-generation B-Series. This chassis was introduced in 1989 under the GMC TopKick and Chevrolet Kodiak names.

Both gasoline and diesel engines were offered on this generation of B-Series. A 6.0L (366 cu in) V8 gasoline engine was offered, allowing potential LPG (propane) or CNG conversion. Late in the 1990s, the 366 V8 was retired in favor of a 454-cubic-inch (7.44 L) V8; GM was the last manufacturer to offer a gasoline engine in a full-size school bus. Caterpillar 3116 turbocharged six-cylinder diesels were offered as well, later models had the Caterpillar 3126 turbocharged six cylinder. Transmissions were either Allison automatics, or a 5 speed manual transmission

When GM replaced the GMT 530 series of medium duty conventionals with the GMT 560 series in 2003, no direct replacement for the B-Series was offered. GM has, however, offered cutaway cabs on their Class 4 and Class 5 models, allowing for body builders to add bus bodies in the same manner (and design) as they would on the full-size van cutaways.


The B-Series chassis was used by a variety of manufacturers and was popular for the availability of both gasoline and diesel engines. Until 1992, the B-Series was available to all manufacturers. However, in a move that crippled GM's marketshare of the school bus market, GM signed an agreement with Blue Bird Corporation for 1992. Under the terms of the agreement (which lasted 10 years), Blue Bird became the only body manufacturer allowed to build buses on the new B-Series chassis and would also be responsible for all distribution and service. The resulting model was named the CV200, and while the GM B-7 chassis was standard, Navistar International and Ford (and later, Freightliner) chassis were available as options.

Manufacturers who used the B-Series before 1992
A 1980s Chevrolet B-Series with a Blue Bird Conventional body


Engine Name Displacement Notes
GM Small-Block V8 5.7 liters (350 cubic inches)
GM Big-Block V8s
  • 6.0 liter (366 cubic inches)
  • 7.0 liter (427 cubic inches)
  • 7.4 liter (454 cubic inches)
  • 8.1 Liter (496 Cubic inches)
The 366-cubic inch V8 was a common basis for second-party conversions for alternative fuels (propane and CNG).

After the 7.4L (454 CI) Engine was discontinued GM used the 8.1L Big Block

Engine Name Displacement Notes
Detroit Diesel "Fuel Pincher" V8 8.2L
Caterpillar 3116 inline-6 6.6L
Caterpillar 3126 inline-6 7.2L

See also[edit]