Navistar International Corp. says it will offer the Cummins ISB 6.7-liter diesel in its International DuraStar medium-duty trucks and CE series IC school buses, but that this doesn't mean it's getting out of the engine business.

The midrange ISB will join the heavy duty ISX15 in the truck lineup, and Navistar will continue building and selling its own MaxxForce DT, MaxxForce 13 and other diesels, said Bill Kozek, Navistar’s president, North America Truck and Parts.

“We are not exiting the engine business,” he added in response to a question during a phone-in press conference with reporters Tuesday afternoon.

“The ISB allows us to get to market today with SCR vehicles,” Kozek said.

Meanwhile, he said, the move "gives us more time to lay out a revised transition plan for our own midrange engine."

For now, Navistar medium-duty diesels, including the DT and MaxxForce 7, will continue as EGR-only engines without selective catalytic reduction, using emissions credits from the Environmental Protection Agency.

“We have sufficient emissions credits to last through next year,” he said.

Cummins SCR equipment is being engineered into Navistar midrange diesels as it was with the MaxxForce 13, and announcements on them will come later.

Offering the ISB “is the same playbook as in heavy duty -- giving customers a choice” between a Cummins product and proprietary engines, Kozek said. “It’s a way to sell more medium-duty trucks.”

The ISX has helped International trucks gain market share, and its Class 8 order share is at more than 20% for the quarter.

Customers have asked Navistar for the Cummins ISB, partly to keep engines common with other truck makes they are running, he said.

“The ISB is a proven engine with 10 million built,” Kozek said, “and experience through our Blue Diamond joint venture with Ford since 2010 has given us experience in building [trucks with] the ISB.” Ford’s F-650 and F-750 share a common chassis with the International DuraStar, “which allows us to ramp up very quickly.”

International dealers will begin taking orders for ISB-powered DuraStars now. Initial production will be this fall and full production will be in December. Installation of ISBs in IC school buses will begin in January.

When asked if the ISB would appear in other medium-duty trucks, such as the WorkStar, Kozek wouldn't say, but he did say that because of packaging problems it definitely won't be a possibility for the TerraStar.

Kozek, who several months ago left Peterbilt Motors to join Navistar, said he couldn’t estimate how many ISBs Navistar would use or what the split between MaxxForce- and Cummins-powered DuraStars will be.