Medium- and heavy-duty truck sales fell for the seventh straight month, dropping 39.3 percent in August from a year earlier.

A total of 31,745 medium- and heavy-duty trucks (classes 4-8) were sold in August compared with 52,334 sold in August of last year.

International and Freightliner continued to fall from their market-leading positions last year.

International's sales dropped 51.9 percent in August to take second place with 5,115 trucks sold. Freightliner's August sales plunged 56.9 percent with 4,738 trucks sold, coming in third among all truckmakers.

Market-leader Ford sold 10,000 trucks in August, down 5.4 percent.

The only truckmaker to post a gain in August was Isuzu, selling 1,276 units, up 13.4 percent.

For the second straight month, only Class 5 trucks avoided a double-digit sales decline. After rising in July, Class 5 truck sales in August dropped 8.9 percent.

Class 8 trucks suffered the most in August, falling 58.9 percent from August last year.

Through August of this year, medium- and heavy-duty truck sales totaled 281,147, down 26.8 percent.