International S-Series (bus chassis)

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International S1723/S1753/S1823/S1853
International 3700/3800
Production 1979–2004
Body and chassis
Class Class 5
Class 6
Class 7
Body style(s) Cowled chassis (conventional)
Related International S Series/International 4000-Series (1989-2001)
Predecessor International Harvester Loadstar 1703/1803
Successor International 3300 (DuraStar)

The bus chassis of the International S-Series is a cowled bus chassis (conventional style) that was produced by International Harvester (later Navistar International) from 1979 to 2004. Produced primarily for school bus applications, the S-Series/3800 bus chassis was used for other uses, including commercial-use buses, cutaway-cab buses. In addition, the chassis formed the basis for front-engine and rear-engine stripped chassis produced for bus applications.

Designed as a replacement for the International Loadstar bus chassis, the S-Series was produced in two distinct generations. During 1989, alongside the rest of the S-Series, International gave its bus chassis a major update, with the model becoming the International 3800. In 2004, the International 3800 ended production, replaced by the International 3300 (based on the 4300, later DuraStar).

In production for 25 years, the S-Series bus chassis was the longest-produced model ever made by International. At its 2004 discontinuation, the International 3800 was the final vehicle sold by International designed before the 1986 launch of Navistar.

S-Series (1979–1989)[edit]

International S-Series "Schoolmaster"
Late 1980s International S-1800 (retired)
Driver's compartment of a typical 1980s International S-Series school bus (Wayne Lifeguard body pictured)
Manufacturer International Harvester
Navistar International
Also called International Harvester S-1723/S-1753
Production 1979–1989
Body and chassis
Body style
  • Cowled chassis
  • School bus
  • Commercial bus
  • Stripped chassis (1853FC)
Platform International S-Series
Transmission 5-speed manual
Allison AT545 4-speed automatic
Allison MT643 4-speed automatic

The Schoolmaster used powertrains and components from the S-Series medium-duty trucks. Two models were available: the S-1700 and the heavier-duty S-1800.


The Schoolmaster changed relatively little over its production run. Many of these changes reflected the transition from International Harvester to Navistar. In 1987, an updated International logo was added to the grille and the steering wheel. Also, in an industry first, all gasoline engines were dropped from the S-Series bus chassis powertrain lineup.

International S-Series "Schoolmaster" Model Designations
Model Names S1700 S1800 1853-FC
S1723 S1753 S1823 S1853
Fuel Type Gasoline Diesel Gasoline Diesel Diesel
Years Produced 1979–1986 1979–1989 1979–1981 1979–1989 1981–1989


International S-Series "Schoolmaster" engine lineup[a][1]
Model Configuration Fuel Type Power Torque
SV-345 345 cu in (5.7 l) V8 Gasoline 158 hp (118 kW)
MV-404 404 cu in (6.6 l) V8 Gasoline 2bbl: 188 hp (140 kW)4bbl: 210 hp (160 kW)
MV-446 446 cu in (7.3 l) V8 Gasoline 235 hp (175 kW)
D-Series 549 cu in (9.0 l) V8 Diesel D-150: 150 hp (110 kW)D-170: 170 hp (130 kW)

D-190: 190 hp (140 kW)

IDI 420 cu in (6.9 l) V8 Diesel 6.9L:170 hp (130 kW)7.3L: 185 hp (138 kW)
444 cu in (7.3 l) V8
Caterpillar 3208 636 cu in (10.4 l) Diesel 225 hp (168 kW)
  1. ^ Engines are International except the Caterpillar 3208.

3800 (mid-1989–2004)[edit]

International 3800
Carpenter Classic 2000 bus 2.jpg
2000–2001 International 3800 (Carpenter Classic 2000 body)
School bus cockpit.jpg
Driver's compartment of a typical 1990s International 3800 school bus
Manufacturer Navistar International
Also called International 3700/3800
Production 1989–2004
Body and chassis
Body style
  • Cowled chassis
  • School bus
  • Commercial bus
  • Front-engine stripped chassis (3900)
  • Rear-engine stripped chassis (3000)
Platform International S-Series
Transmission 5-speed manual
Allison AT545 4-speed automatic
Allison MT643 4-speed automatic
Successor International 3300

In 1989, Navistar redesigned the S-Series medium-duty conventionals for the first time since 1979; the medium-duty trucks were renamed the 4000-Series. As part of the redesign, the school bus chassis was given a more aerodynamic hood that better integrated the front bumper. On the inside, a two spoke-steering wheel was introduced along with a new instrument cluster. For the first time, the school bus chassis received a separate model designation; the S-1703 was replaced by the 3700; and the S-1803 was replaced by the 3800.


As with its predecessor, the 3800 would change very little over its 15 years of production. In 1991, the 3600 semi-forward control variant was introduced; this was a chassis designed for the Thomas Vista. After 1994, the lower-GVWR 3700 was discontinued. For 1995, along with all other International medium-duty trucks, the 3800 received chrome hood badges denoting the model series and its engine type; the grille badging changed from red to chrome.

A key event that would affect school bus manufacturing during the later 1990s was the completion of the acquisition of AmTran by Navistar in April 1995. By the end of the decade, AmTran buses would begin to start wearing International badging on the body as well. To promote the change, in 2002, International redesigned the hood for its conventional bus, dubbed the International IC. These wore vertical grille slats instead of horizontal ones seen since 1989 (although the horizontal grille slats continued to be produced for the 3800 until 2004). As it was a change intended to promote IC Corporation, chassis destined for Blue Bird or Canadian manufacturer Corbeil were still received with the standard hood and grille design.

International S-Series "Schoolmaster" Model Designations
Model Names Conventional Stripped Chassis
3400 3600 3700 3800 3900FC 3000
Fuel Type Diesel
Years produced 1991–1998 1989–1994 1989–2004 1990–2010 1996–present



Navistar 3400 in use as a shuttle bus.

The 3400 was a chassis designed in the same fashion as a Type A cutaway school bus. To achieve a higher GVWR and allow for higher durability, instead of a van, the medium-duty International 4700 was used as a base. While primarily used by builders of transit buses and specialty vehicles, several body manufacturers (Mid Bus and U.S. Bus) would adopt the 3400 for school bus use.

In the school bus industry, Mid Bus and U.S. Bus both developed products based on the 3400, but the chassis became more popular in the transit and specialty vehicle industries instead.

All versions of the 3400 were powered by the 7.3L IDI and T444E V8 engines and used hydraulic brakes. As the 4700 was discontinued after 2001, the 3400 was replaced by the 3200 based upon the new-generation 4000-Series trucks (later the DuraStar); currently, the 3200 is used only for transit bus, commercial bus, and specialty vehicle applications.


Thomas Vista, the bus body paired with the International 3600 chassis.

The 3600 was a chassis custom-designed for the Vista from Thomas Built Buses. The Vista combined design elements of a conventional and a forward control school bus. In comparison to a conventional, the driver sat further forward, closer to the front axle. Although much of the engine was located next to the driver like a transit-style bus, access from the front was also maintained via a traditional much-shortened hood. The 3600 chassis was designed in much the same fashion as International's step van chassis, borrowing many components from the 3800.

As it was originally designed specifically for the Vista's body, no other body manufacturers developed their own product lines based on the 3600. It was produced from 1991 until 1998 when Thomas chose to discontinue Vista production after the body manufacturer's purchase by Freightliner.


1994 International 3700 with Thomas body

From 1989 to 1994, International offered two versions of its conventional school bus chassis (as it had with the S-Series). The 3700 was the lighter-GVWR model of the lineup; only minor differences in powertrain and weight ratings differentiated it from the 3800. The 3700 only was produced with the 7.3 engine.

After 1994, the 3700 was discontinued.


As a replacement for the outdated 1853FC, International introduced the 3900 in 1990 as its forward-control bus chassis. Although primarily used by Ward/AmTran/IC, it has been used by a wide variety of other manufacturers of similar buses. In 2010, International ended production of the 3900.


The 3800 is notable for being the first American school bus chassis to have an engine lineup consisting only of diesel engines. Unlike its S-Series predecessor, the 3800 used an all-International lineup of diesel engines.

Inline-six diesel
  • DTA360 (1989–1994)
  • DT408 (1994–1995)
  • DTA466 (1989–1998)
  • DT466 Mechanical Injection
  • DT466E Electronic Injection (1996–2005)
V8 diesel
  • IHC 7.3L IDI (1989–1994)
  • T444E (1994–2004)
  • Spicer 5-Speed Manual
  • Eaton-Fuller 6-Speed Manual
  • Spicer 6+1 Manual
  • Allison AT545 automatic
  • Allison MT643 automatic
  • Allison A2000 automatic

Stripped Chassis (1981–present)[edit]

2005-2007 IC FE300 on an International 3900FC chassis

Along with the traditional conventional-style cowled chassis, International produced several stripped-chassis variants for transit-style school buses. Using many chassis and powertrain components from the S-Series, the front-engine 1853FC (FC=Forward Control) was produced from 1981 to 1989. Unlike the conventional, it was powered exclusively by diesel engines. In 1990, the 1853FC was replaced by the more advanced 3900. As with its predecessor, it again shared powertrain and chassis components with its conventional counterpart. In fixing a key drawback of the 1853FC, the 3900 would significantly reduce the interior space needed for the engine, freeing up space for the driver's compartment and front stairwell. The 3900 was produced until 2010.

In 1996, International introduced its first rear-engine stripped chassis since the early 1970s as the International 3000 became the chassis for the all-new AmTran RE. As with the 3900, the 3000 shared chassis and powertrain components with the 3800. Unlike its front-engine counterpart, the 3000 was designed for the use of both V8 and inline-6 diesel engines. Almost used exclusively used for AmTran and IC school buses, the 3000 remains in production as of 2014.

Body manufacturers[edit]

For its production run, the S-Series was used by many manufacturers of Type C school buses in North America. The same was common practice for the 3800 for the early part of its production run. Following the completion of the 1995 acquisition of AmTran, school bus production began to change as chassis suppliers began to align themselves with body manufacturers. The market share of International actually grew as several body manufacturers such as Wayne and Carpenter would close down and Ford and General Motors were gradually shut out of full-size bus production. By 2004, there were only three body manufacturers of full-size buses (Blue Bird, IC Corporation, and Thomas) and three chassis manufacturers (Blue Bird, Freightliner, and International). Navistar, the parent company of IC Corporation, was the lone chassis manufacturer that sold bus chassis to other body manufacturers.

International S-Series bus chassis usage by school bus manufacturers, 1979-2004
Body manufacturer Chassis variants Notes
Conventional Front-engine Rear-engine












American Transportation Corporation (AmTran)
1996 AmTran IC (Fairfax County Public Schools).jpg
AmTran Volunteer (1993-1996)
AmTran CS (1997-2002)
AmTran Genesis (1992-1997)
AmTran FE (1998-early 2002)
AmTran RE (1996-early 2002)
Blue Bird Corporation
Schulbus Hamburger Hummelbahn02.jpg
Blue Bird Conventional (1979-1989) Blue Bird Conventional (1989-2004) Replaced by Blue Bird SBCV (based on International 3300) and Blue Bird Vision.
Carpenter Body Works
Carpenter Classic 2000 bus 1.jpg
Carpenter Classic (1979-1989) Carpenter (Crown) Classic (1989-1999)
Carpenter Classic 2000 (late 1999-2001)
Carpenter Cavalier (1983-1988) Carpenter Counselor (1991-1993) From 1996 to 1999, Carpenter used the Crown by Carpenter brand name on their buses.
Gillig Corporation Gillig Coach (1979-1981) The last Gillig Type C bus (Gillig Coach School Bus) was built in 1981; very few were produced.
Integrated Coach Corporation (IC)
Church bus Highland Heights United Methodist Church Memphis TN 06.jpg
International IC (2001)
International CE-Series (late 2001-2004)
International FE-Series (2002-2010) International RE-Series (2002-present) The version of the 3800 used by IC wore a modified hood.
Les Enterprises Michel Corbeil EMC 1st Premier (c. 1991-1995)
Corbeil Conventional (c.1996-c.2004)
EMC-3900 (c. 1995-2000) EMC-3900 RE (c.2000-2001) Corbeil Type C buses were not sold in the United States.
Mid Bus The Mid Bus SC is a school bus built on the International 3400 cutaway-cab chassis (with a truck cab and driver-side door); the SC was built during the mid-1990s.
New Bus Company 1988-1989
Superior Coach Company Superior Pioneer (1979-1985) Superior ended production of Type C buses in 1985 to concentrate on Type A buses (see Mid Bus)
Thomas Built Buses, Inc.
Coastal City School Bus crop.JPG
Saf-T-Liner Conventional (1979-1989) Saf-T-Liner Conventional (1989-2001)
Ward Body Works Ward Volunteer (1979-1989) Ward Volunteer (1989-1992) Ward President (1981-1986) Ward Senator (1991-1992) Non-school bus versions of the Volunteer built after 1980 were sold under the AmTran name.
Wayne Corporation
Old School bus, Nahunta.JPG
Wayne Lifeguard (1979-1989) Wayne Lifeguard (1989-1992) Wayne Lifestar (1991-1992)
Wayne Wheeled Vehicles Wayne Lifeguard (1992-1995)

See also[edit]


  1. ^ "International Truck Specifications - S Line". Wisconsin Historical Society. 2013. Retrieved 2014-02-27. 

External links[edit]