U.S. sales of medium- and heavy-duty trucks were down 5.9% – down to 38,372 units – in October compared to a year ago, according to WardsAuto data.Class 8 posted the largest drop of 15.7% with 19,252 deliveries, according to the report. Overall medium-duty deliveries were up 6.7% in October, WardsAuto said. Class 7 posted a 6.5% gain with a sales of 5,282 units. According to the report, Class 6 was the top performer, with a 16.4% jump. In Canada, medium- and heavy-duty truck sales fell 11.8% in October, and all segments except for Class 4 were down from a year ago, WardsAuto said. Deliveries in October totaled 3,736 units compared to 4,079 from the previous year.Class 4 was the only segment to enjoy an increase – a 16.6% jump in sales last month. WardsAuto has more.