INDIANAPOLIS. Isuzu Commercial Truck of America unveiled its 2014-15 model-year N-Series diesel truck models this week at the NTEA Work Truck Show. The company also announced that it would extend its 24 months/60,000 mi. covered maintenance program to all the diesel models sold through June 30, 2014. The changes were announced during Isuzu’s continuing celebration of the 30th anniversary of Isuzu trucks in the U.S. market.