Navistar will offer the Cummins Westport ISL G natural gas engine in the International TranStar and WorkStar trucks.

More than 13,000 ISL G engines have been produced since it was first introduced in 2007. While initial success was in the transit and refuse markets, more recently the conventional truck market has shown an interest in natural gas.

The Cummins Westport ISL G, an 8.9-liter stoichiometric cooled-exhaust gas recirculation engine, is certified to 2010 EPA emissions.

"Adding Navistar completes the listing of the ISL G with all major North American truck OEMs and reaffirms Cummins Westport's position of market leadership for natural gas engines," says Roe East, president of Cummins Westport.