LISLE, Ill. — Navistar has announced it has finalized its supply agreement with Cummins, to offer the ISX 15 in International ProStar, PayStar and 9900 models.

Navistar will also use Cummins’ selective catalytic reduction (SCR) system on its trucks.

The company announced the “definitive, long-term supply agreements” this morning, though it’s been known for some time that Navistar International would be offering the ISX 15 and using Cummins’ exhaust aftertreatment system.

“This agreement represents a natural extension of the long-standing relationship between Navistar and Cummins and our history of collaboration in serving our mutual customers,” said Troy Clarke, Navistar president and COO. “With the addition of the Cummins ISX15 and the use of the proven Cummins aftertreatment system, we are on a clear path to providing customers with proven, reliable and fuel-efficient clean engine technology.”

Navistar said engineering teams from both companies have been working closely together to integrate vehicle, engine and emissions aftertreatment systems.

Navistar will begin its initial pilot builds of ProStar+s with the Cummins ISX 15 in November with the first shipments due in December, the company announced. The ProStar+ with International MaxxForce 13 with SCR will enter initial pilot production in March 2013 with full production set to begin the following month.

The remainder of International’s truck line will be rolled out with SCR over the course of 2013 “based on volume and customer demand,” Navistar announced. During the transition, the company says it will continue building and shipping EPA-compliant trucks by redeeming its remaining emissions credits and paying non-conformance penalties to the EPA.