The bus chassis variant of the International Loadstar is a cowled bus chassis that was produced by the International Harvester Company from 1961 to 1978, beginning with the 1962 model year. Produced primarily for school bus applications, the chassis was also produced for other applications, including commercial-use buses. In addition, the cowled chassis formed the basis for front-engine and rear-engine stripped chassis produced for bus applications. For 1979, the model was replaced by the newer International S series "Schoolmaster".
Models had vacuum assisted hydraulic drum brakes standard. Air over hydraulic and full air brakes were available. A driven front axle and tandem rear axles were available on some models. Loaded weights were from and up to .
Most models were recognizable by their grey grill, curved fenders and "butterfly" hood. From the 1972 to 1978 model years, a squared-off, one-piece, fiberglass tilting hood was included as a option for school buses.
Gasoline and mid-range diesel engines were used. The butterfly hood of the Loadstar meant that V-8 engines fit better than straight-six engines. The tilting hood of the Loadstar fits both V-8 and straight-six engines.
The V-345 was the primary engine of the 1603 between 1962 and 1973, at the time when the model was discontinued. They are overhead valve gasoline V8s. They developed respectively.
The MV 404 was introduced for 1974. It was a overhead valve gasoline V8 with a 4-barrel carburetor. It developed and of torque. It became standard on the 1703 and 1803.
Mid-range diesels were International V8s up to , including the 1803 from 1974 to 1978.
Five- and four-speed manual transmissions were used both on the 1603 and the 1703. A 4-speed Allison automatic transmission was available on any school bus model. Diesel models were available with 5- and 10-speed Allison or Roadranger automatic or manual transmissions.
Over its 16-year production, the Loadstar was bodied by many bus manufacturers, primarily for use as a school bus. After the 1977 federal safety standards came into effect, the Loadstar 1703/1803 "Schoolmaster" ended production in 1978, and was replaced by the S-Series for the 1979 model year.