For 1981, International Harvester introduced the CO9670 cabover to replace the Transtar II CO4070 in production since 1974. Sharing its doors with the Transtar 4300, the C09670 featured a wider cab, and larger windows and windshield. The trapezoidal grille used on all large International cabovers since 1965 was redesigned to include the headlights.

In place of the massive Cummins KT450 and Caterpillar 3408 engines included on the Transtar II, the CO9670 was powered by the smaller-displacement 855 cubic-inch N-Series Cummins diesel. In twin-turbocharged configuration, the engine produced 475 hp.

In 1989, Navistar updated the CO9670, rebranding it the International 9600.

For 1988, Navistar redesigned the 9000-series cabovers, allowing for the addition of a set-back front axle version. Although visually similar to the 9600 from the axles above, the 9700 was given many aerodynamic enhancements, including lower body skirting, an enhanced front bumper, and faired-in front turn signals. The front-axle configuration allowed for a complete redesign of the interior, allowing for a completely flat floor; Navistar was one of the first American manufacturers to market a cabover truck without an intrusion from the engine separating the driver and passenger seats, allowing walk-in access to the sleeper compartment.^[1][2] As an option, Navistar offered a sleeper compartment with a roof extending above the front seats.^[3]

After 1998 production, the 9700 and 9800 were withdrawn from the 9000 series as International exited COE production in North America.

Following the discontinuation of the 9000-series COE in the North American market, Navistar continued cabover production by sending the tooling for the model line to Brazil. Outside of Brazil, the 9800i was exported throughout South America, with right-hand drive production exported to New Zealand and South Africa.

Sharing much of the cab of the previous generation, the third generation shed the trapezoidal grille design of International COEs used since 1965 in favor of a square grille (in line with 9000i-series conventionals).

To meet local specifications and to provide better quality assembly, the assembly operation for the 9800i for the New Zealand market was shifted from South America to New Zealand in 2004.^[4]

In 2015, production of the 9800i was halted.^{[citation needed]} In August 2017,^[5] the truck was still sold in South Africa. Production of the 9000 series continues in the New Zealand market.^[4]

In 2008, the 9800i was completely redesigned for the New Zealand market in order to accommodate Euro 4 emissions standards. The redesign included a raised cab, new cooling panels and an upgraded interior trim. The design also included a new grill, now elongated to fit the new cooling requirements. The upgraded EPA-04 engine raised the horsepower from 475hp to 615hp with 2050 lb/ft torque.

Euro 5 emissions were added in 2012, and the emissions technology changed over from EGR to SCR. Additionally, the cab received another facelift.^[4]

Due to law changes in New Zealand around vehicle dimensions, set forward axle trucks became more advantageous. In response, the 9800i was remodeled from being a 1400mm set back axle to a 920mm set forward one. This change came with a rebrand to the 9870, a new grill and new cooling package.^[4]