Rush Enterprises, which operates one of the largest Peterbilt heavy-duty truck dealerships in North America, said it's on track to post earnings of 18 to 20 cents per share for the third quarter, compared to earnings of eight cents per share in the same period last year. Analysts predicted that San Antonio-based Rush would earn 15 to 16 cents per share in the third quarter of this year. Rush attributed rising earnings to higher new truck sales volumes and a stronger used truck market resulting from the mandated introduction of low-emission diesel engines on October 1. However, the company expects to see a decline in new truck demand after October 1 because of those new engines. So far it has been a good year for Rush, despite the overall economic downturn and continued soft heavy-truck sales. In the second quarter, Rush posted overall gross revenues of $193.1 million, a 3.1% decrease from the second quarter of 2001, but it saw a 36.3% jump in net income to more than $2 million. The company's heavy-duty truck segment posted revenues of $160.7 million in the second quarter, up slightly from $160 million in the same period last year, selling 972 and 535 new and used trucks, respectively, compared to 998 and 524 new and used in the same period in 2001. Parts, service and body shop sales at its dealership locations increased 15.7% to $56.3 million in the second quarter compared to the same period last year.