Medium- and heavy-duty truck sales fell 3.9% in February, with Class 8 the sole declining group, WardsAuto data shows.

Class 8 deliveries slid 15.2% to 12,546 as International, PACCAR and Volvo Truck saw double-digit percentage declines.

PACCAR’s Kenworth brand slipped the most, down 38.4% from like-2012.

No Class 8 manufacturer landed in positive territory, but Daimler’s Freightliner saw the smallest decrease vs. year-ago, down 2.2%. The relatively minor loss in the face of bigger declines among competitors boosted Freightliner’s share to 43.1% from 37.4% in February 2012.

Total medium-duty deliveries tallied 12,270, up 11.3% from year-ago.

Class 7 sales were flat, up 0.3% to 3,377. UD Trucks’ imported models gained slightly, while PACCAR’s Kenworth again took the biggest plunge, down 52.8%, and Ford sales fell 43.5%.

Class 7 volume runner-up International dipped 3.3% vs. February 2012, widening its gap with No.1 Freightliner, which saw sales rise 27.1%.

Boosted by a 341.4% gain at Ford, Class 6 recorded the largest increase of any big-truck group last month. Ford sold 822 Class 6 units vs. 194 in like-2012.

Ford’s performance, plus increases by segment-leading Daimler and Hino, offset losses elsewhere. UD Trucks’ drop of 39.9% was the group’s largest, followed closely by PACCAR’s 37.2%.

Class 5 sales grew 5.6% last month, but most players posted declines.

Isuzu’s 40.7% hike was the largest in the segment, while International gained 29.7% and Ford 23.5%. Chrysler recorded the biggest drop (52.6%), followed by PACCAR (47.9%).

A 12.6% gain for Class 4 sales was driven by a 7.9% rise in demand for domestically built Isuzu models and a 130-unit increase at Ford, giving the Blue Oval brand a 25.0% segment share compared with year-ago’s 1.9%. Isuzu’s imported trucks fell 23.8%, knocking almost 20 points off its segment market share.

Through February, sales of medium- and heavy-duty trucks in the U.S. ran 3.2% below the same period year-ago. Class 8 volume alone is down 13.0% year-to-date.

Heavy-duty inventories held steady at 62 days’ supply, but actual units in stock declined to 32,620 from 38,219 year-ago.

Medium-duty supplies fell to 70 days’ from 82, with inventories declining to 35,955 units from 37,546 in like-2012.

In other big-truck news, Navistar International names Troy Clarke CEO, replacing interim CEO Lewis Campbell. Clarke previously was chief operating officer for the beleaguered truck manufacturer.

“We believe that Troy will be able to focus the company on its core business, execute on aggressive cost and market share targets and ultimately succeed in leading Navistar to the dominant position in the North America heavy truck market,” Navistar investor Carl Icahn is quoted as saying.

Navistar last week reported a 12% decline in revenue for its fiscal first quarter, but is predicting a second-half market-share increase as it looks for ways to cut costs.