CHICAGO — Class 8 truck and engine builder Navistar International Corp. posted a $123-million loss in its fiscal first quarter, down 19.6 percent from a $153-million loss a year earlier, on sales that shrank 12.4 percent to $2.64 billion.

The decline in revenue reflected lower overall industry demand and lower market share as a result of the company’s clean-engine strategy transition.

"We are beginning to see concrete progress on each of our near-term priorities—improving our quality, launching our new SCR (selective catalytic reduction) engine programs on schedule and delivering on our 2013 operating plan, which will put us on a path to profitability," chairman and chief executive officer Lewis B. Campbell said in a March 7 statement.

"We have made solid progress," he said, noting that Navistar had submitted its 13-liter SCR engine for certification ahead of schedule and earlier this week had kicked off pilot production for ProStar+ vehicles using that engine.

The Lisle, Ill.-based company also has "aggressively manag(ed) inventories and significantly reduc(ed) discretionary spending enterprisewide," Campbell said. "We recognize the need to do even more," given weak first-half industry volumes.

He said Navistar’s market share should begin to improve in the second half with the full launch of its clean-engine lineup.

Navistar also is streamlining. It recently sold its equity interests in truck and engine joint ventures in India, sold its Workhorse Custom Chassis brand and sublet a portion of its Cherokee, Ala., manufacturing facility to Chicago-based FreightCar America Inc.