International S series

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International S series
1989 International S1754 dump truck.jpg
1989 International S-1700 single-axle dump truck
ManufacturerInternational Harvester (1978-1986)
Navistar International (1986-2001)
Also calledNavistar International 4000 series
Navistar International 8000 series
Body and chassis
ClassClass 6-7 medium-duty truck
Body style
Truck (conventional)
  • Tractor
  • Straight truck
RelatedInternational S series "Schoolmaster"
International 3800
197–236 hp (147–176 kW)
150–500 hp (110–370 kW)
PredecessorInternational Harvester Fleetstar (to 1978)
International Harvester Loadstar (1962-1979)
SuccessorInternational 4000 series/DuraStar

The International S series is a range of trucks that was manufactured by International Harvester (later Navistar International) from 1977 to 2001. Introduced to consolidate the medium-duty IHC Loadstar and heavy-duty IHC Fleetstar into a single product range, the S series was slotted below the Transtar and Paystar Class 8 conventionals.

The IHC S series was produced in a number of variants for a wide variety of applications, including straight trucks, semitractors, vocational trucks, and severe-service trucks. Additionally, the S series was produced in other body configurations, including a four-door crew cab, cutaway cab, cowled chassis, and a stripped chassis (primarily for school buses). The chassis was produced with both gasoline and diesel powertrains (the latter exclusively after 1986), single or tandem rear axles, and two, four, or, six-wheel drive layouts.

The last complete product line designed within the existence of International Harvester, the S series was produced in its original form through 1989. To reflect the change to Navistar, a major facelift updated the exterior and interior of many models, which were produced through 2001. As a replacement for the S series, Navistar introduced the 4000 series and 7000 series (known as the International DuraStar and International WorkStar since 2008).

S series (1956–1957)[edit]

1956 International Harvester S100

As a nameplate, International Harvester first introduced the S series for 1956. Available as the IHC light-duty and medium-duty range, the predecessor R series remained in production. In addition, the S series formed the basis for its own generation of the IHC Travelall wagon, marking the introduction of a four-wheel drive option for the model.

The heaviest version (the S1840) was produced with a GVWR of 24,000 lb (10,886 kg), powered by a 308 ci "Black Diamond" gasoline engine.[1]

Production of the light duty S series ended in 1957, when it was replaced by the A series.[2] The S-184 heavy version was produced by the Brazilian subsidiary of International Harvester, until its 1966 purchase by Chrysler.[3]

First generation (S series; 1978–1989)[edit]

Navistar 2500 in use as a municipal service truck.

In April 1977, International Harvester unveiled the medium-duty S series at an event at the New Orleans Superdome.[4] Initial sales[when?] were of heavier-duty 2200, 2500, and 2600 models (28,000-45,000 lb GVW[a]), replacing the Fleetstar. In the summer of 1978,[5] lighter-GVWR models (replacing the Loadstar) were released for sale.

Following the discontinuation of the IHC pickup-truck line in 1975, the S series was designed with a model-specific cab, replacing the pickup-truck cab used for the Loadstar (designed for the 1957 A series). More vertically-oriented than its predecessor, the design was much wider as well. To lower maintenance costs, all windows in the cab were designed with flat glass, including the windshield. Similar in style to the tilting hood introduced for the Loadstar in 1972, all S-series trucks were given a tilting fiberglass hood.

The S series would be produced throughout the 1980s largely unmodified. 1987 would mark several changes to the S-series trucks. To reflect the corporate change of the company from International Harvester to Navistar International, S-series trucks saw changes in their badging (alongside all International vehicles). On the grille, the word "International" across the top of the grille was replaced by a red Navistar "diamond" logo alongside "International" in red at the bottom left of the grille. Inside, the IHC "tractor" logo on the steering wheel was replaced by a Navistar diamond logo. In a major shift, for 1987, International became the first truck manufacturer to produce a medium-duty product line powered exclusively by diesel engines.


Originally intended to use the International Tristar nameplate, the S series consolidated the aging Loadstar and Fleetstar trucks under a single product line. Tandem-axle (6x4) versions of the S series were named F-series trucks.[6]

Class 6 trucks[edit]

The S1600, S1700, S1800, and S1900 were introduced in 1979. Replacing the International Harvester Loadstar model line, the model was produced in a number of configurations, with single and tandem rear axles, 4x4/6x6 drive options, and gasoline and diesel engines. The S-1800 and S-1900-were produced as both semitractors and straight trucks, while the S-1700 and S-1800 were used in the production of International Harvester bus chassis (primarily for school bus use).

Class 7-8 trucks[edit]

Introduced in 1978 as the replacement for the Fleetstar, the S2100 and S2200 were joined by the severe-service S2500 and S2600, slotted below the International Paystar 5000. Configured primarily as tractors, the S2100 was fitted with a sloped hood. To accommodate larger-bore diesel engines under a standard-length hood, the S2200 was fitted with a widened cab (distinguished by a two-piece windshield).

In 1982, the S2300 was introduced; the model line was essentially an S2100 with International diesel engines replaced with Cummins-sourced powertrains.[7]

1978–1983 models

Model[8] Max. front GAWR[b] Max. rear GAWR Engine[c] Trans [d]
1600 4x2 5,000 lb (2,300 kg) 15,000 lb (6,800 kg) V-345 4M, 4A
Binder 4x2 1,600 lb (730 kg) 15,000 lb (6,800 kg) V-345 5M, 4A
1700 4x2 7,500 lb (3,400 kg) 15,500 lb (7,000 kg) MV-404, D-170 10M, 5A
1800 4x2 6,000 lb (2,700 kg) 15,500 lb (7,000 kg) MV-446, DT-466 13M, 5A
1800 4x4 9,000 lb (4,100 kg) 15,500 lb (7,000 kg) MV-446, DT-466 5M, 4A
1900 4x2 9,000 lb (4,100 kg) 17,500 lb (7,900 kg) MV-446, DT-466 10M, 5A
1900 6x4 9,000 lb (4,100 kg) 34,000 lb (15,000 kg) MV-466, DT-466 10M, 5A
1900 6x6 9,000 lb (4,100 kg) 34,000 lb (15,000 kg) MV-466, DT-466 5M
2100 4x2 9,000 lb (4,100 kg) 17,500 lb (7,900 kg) V-537, DT-466 10M
2100 6x4 9,000 lb (4,100 kg) 34,000 lb (15,000 kg) V-537, DT-466 10M
2200 4x2 10,800 lb (4,900 kg) 23,000 lb (10,000 kg) Cat 3406 13M
2200 6X4 12,000 lb (5,400 kg) 23,000 lb (10,000 kg) Cat 3406 13M
2300 4x4 12,000 lb (5,400 kg) 41,000 lb (19,000 kg)
2500 4x2 16,000 lb (7,300 kg) 29,000 lb (13,000 kg) Cat 3406 13M
2500 6X4 18,000 lb (8,200 kg) 44,000 lb (20,000 kg) Cat 3406 13M
2600 4x2 16,000 lb (7,300 kg) 29,000 lb (13,000 kg) Cum PT 13M
2600 6X4 18,000 lb (8,200 kg) 44,000 lb (20,000 kg) Cum PT 13M

Second generation (1989–2001)[edit]

During 1989 production, the S-series line underwent a major upgrade. Although the cab itself was retained, interiors saw complete redesigns, with all-new dashboards and interior controls; a two-spoke steering wheel replaced the previous three-spoke design in use. In the interest of aerodynamics, many models saw redesigned hoodlines, with halogen headlamps and wraparound turn signals.

During its production life, the second-generation vehicles saw few major changes, with the exterior remaining nearly unchanged throughout its entire production. In contrast, the interior would see several updates. In 1992, the instrument panel was redesigned, with the rest of the interior redesigned in 1995.


International 8100 4x2 tractor towing solar panels

As part of the redesign, Navistar split its medium-duty S-series range into three separate model lines. The 4000 series served as the replacement for the S1600 through 1900 Class 5-7 trucks (with bus chassis rechristened the 3000 series), while the 8000 series replaced the S2100 and S2300 (the wide-body S2200 was discontinued). Again slotted below the Paystar, the 2500 and 2600 severe-service trucks dropped their S-series prefix.

Class 5-7 trucks[edit]

Replacing the S1600 through S1900, the 4000 series was again produced in a number of configurations, with single and tandem rear axles, 4x4/6x6 drive options. Produced exclusively with diesel engines, the 4000 series was produced with the IDI V8 and DT360/DT466 engines.

The 4000 series was produced through 2001, when it was replaced by an all-new 4000 series (now the International DuraStar).

Class 7-8 trucks[edit]

Replacing the S2100,and S2300, the 7100 and 8100 were introduced in 1989; the wide-body S2200 was not replaced. Configured nearly exclusively as tractors, the 8000 series was powered by the Cummins L10 diesel; the 7100 was a variant powered by the DT466.

The 8000 series was produced through 2001, when it was replaced by an all-new 8000 series (now the International Transtar).

Severe-service trucks[edit]

Again slotted below the Paystar, the 2500 and 2600 severe-service trucks dropped their S-series prefix. During the 1990s, the set-back axle 2674 was restyled with the aerodynamic hood of the 8300. The 2500/2600 remained in production through 2003, outlasted only by the 3800 school-bus chassis.

Model Replaced Notes
4500 S1600 Low-profile chassis
4700 Low-profile chassis
4900 S1800 Available with tandem rear axles.
8100 S1900
8200 Long hood semi-tractor
8300 Long hood semi-tractor
2500 Long hood
2600 Long hood, set-back front axle
Available in 4x2, 4x4, 6x4, and 6x6 drive
3600 Australasia-specific model, similar to 2500
model-specific hood

Bus use[edit]

Wayne Lifeguard school bus with International 3800 chassis (retired)
Navistar International bus in Mexico.

Throughout its production, the S series would be used as a cowled chassis for bus manufacturers. While used primarily for yellow school buses in the United States and Canada, the S series also was used outside of North America as a basis to produce other types of bus bodies. Introduced in 1979, the bus variant of the S series would be one of the final models designed by International Harvester before its transition to Navistar. In 1989, the S-series bus chassis was rechristened the 3000 series with the fitment of the new-generation Navistar cowl.

Produced until 2004, the bus chassis would outlive its truck counterpart by three years; its 25-year production run is the longest of any product ever sold by International Harvester or Navistar.


Models Replaced Notes


Loadstar 1703

Loadstar 1803

3600 See Thomas Vista

Produced 1992-1998






Model[e] Displacement Type[f] Power Torque
V-345 345 cu in (5.7 l) G V8 197 hp (147 kW) 309 lb⋅ft (419 N⋅m)
V-392 392 cu in (6.4 l) G V8 236 hp (176 kW)
MV-404 404 cu in (6.6 l) G V8 210 hp (160 kW) 336 lb⋅ft (456 N⋅m)
MV-446 446 cu in (7.3 l) G V8 235 hp (175 kW)
D-190 549 cu in (9.0 l) D V8 190 hp (140 kW) 340 lb⋅ft (460 N⋅m)
IDI-420 420 cu in (6.9 l) D V8 170 hp (130 kW)
IDI-444 444 cu in (7.3 l) D V8 190 hp (140 kW) 388 lb⋅ft (526 N⋅m)
Cat 3208 636 cu in (10.4 l) D V8 210 hp (160 kW)
Cat 3406 893 cu in (14.6 l) D I6 380 hp (280 kW)
Cum NTC-350 855 cu in (14.0 l) D I6 350 hp (260 kW)
Cum M11 659 cu in (10.8 l) D I6 500 hp (370 kW) 1,550 lb⋅ft (2,100 N⋅m)
DD 6-71 426 cu in (7.0 l) D I6 230 hp (170 kW)
DD 6V-92 552 cu in (9.0 l) D V6 335 hp (250 kW)
DD 8V-92 736 cu in (12.1 l) D V8 400 hp (300 kW)

See also[edit]


  1. ^ Gross Vehicle Weight Rating is the loaded weight of the truck.
  2. ^ Gross Axle Weight Rating is the loaded weight of the axle.
  3. ^ Highest rated gasoline, diesel engine.
  4. ^ Speeds in manual(M), automatic(A) transmission
  5. ^ Engines are International unless noted as Caterpillar(Cat), Cummins(Cum), or Detroit Diesel(DD).
  6. ^ Gasoline(G), diesel(D), inline(I), (V), and number of cylinders.


  1. ^ Crismon, Frederick W. (2002), International Trucks (2 ed.), Minneapolis, MN: Victory WW2 Publishing, p. 272, ISBN 0-9700567-2-9
  2. ^ "International Harvester History: Trucks". International Harvester. 1961.
  3. ^ Shapiro, Helen (Winter 1991). "Determinants of Firm Entry into the Brazilian Automobile Manufacturing Industry, 1956-1968". The Business History Review. 65 (4): 879. doi:10.2307/3117267. JSTOR 3117267.
  4. ^ Crismon, p. 485
  5. ^ Crismon, p. 492
  6. ^ Crismon, p. 495
  7. ^ "Question about International S-series trucks". Retrieved 2017-05-07.
  8. ^ "International Truck Specifications – S Line – 1956–1983". Wisconsin Historical Society. 2013. Retrieved 2014-10-28.
  • American Truck & Bus Spotter's Guide: 1920-1985, by Tad Burness.
  • International Trucks, by Frederick W. Crismon

External links[edit]