Truck makers and carriers warned the U.S. lacks sufficient domestic supply of key components like transmissions, axles and cooling modules, making parts tariffs especially disruptive. Companies including Paccar and Ford supported tariffs on fully built trucks but cautioned that higher parts tariffs could add billions in costs and hinder future investment. Questions Remain Over USMCA and Cross-Border ManufacturingOf particular importance to most truck manufacturers is whether and to what extent the United States-Mexico-Canada Agreement plays a role, as several truck manufacturers have factories in Canada and Mexico. One analyst noted that the new tariffs could serve as an offset to earlier tariffs that have affected domestic truck manufacturers. “On the parts tariffs side, for the vehicles we do build in the United States, there are a lot of parts that we don’t make in the U.S.,” he said.